Delivery device comprising gas diffuser for thin film deposition

ABSTRACT

A process for depositing a thin film material on a substrate is disclosed, comprising simultaneously directing a series of gas flows from the output face of a delivery head of a thin film deposition system toward the surface of a substrate, and wherein the series of gas flows comprises at least a first reactive gaseous material, an inert purge gas, and a second reactive gaseous material, wherein the first reactive gaseous material is capable of reacting with a substrate surface treated with the second reactive gaseous material. A system capable of carrying out such a process is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. application Ser. No.11/392,007, filed Mar. 29, 2006 by Levy et al. and entitled, “PROCESSFOR ATOMIC LAYER DEPOSITION,” U.S. application Ser. No. 11/392,006,filed Mar. 29, 2006 by Levy et al. and entitled “APPARATUS FOR ATOMICLAYER DEPOSITION,” U.S. application Ser. No. 11/620,744, filedconcurrently by Levy et al. and entitled “DEPOSITION SYSTEM AND METHODUSING A DELIVERY HEAD SEPARATED FROM A SUBSTRATE BY GAS PRESSURE,” andU.S. application Ser. No. 11/620,738, filed concurrently by Levy et al.and entitled “DELIVERY DEVICE FOR DEPOSITION,” all four identifiedapplications incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention generally relates to the deposition of thin-filmmaterials and, more particularly, to apparatus for atomic layerdeposition onto a substrate using a distribution head directingsimultaneous gas flows onto a substrate.

BACKGROUND OF THE INVENTION

Among the techniques widely used for thin-film deposition is ChemicalVapor Deposition (CVD) that uses chemically reactive molecules thatreact in a reaction chamber to deposit a desired film on a substrate.Molecular precursors useful for CVD applications comprise elemental(atomic) constituents of the film to be deposited and typically alsoinclude additional elements. CVD precursors are volatile molecules thatare delivered, in a gaseous phase, to a chamber in order to react at thesubstrate, forming the thin film thereon. The chemical reaction depositsa thin film with a desired film thickness.

Common to most CVD techniques is the need for application of awell-controlled flux of one or more molecular precursors into the CVDreactor. A substrate is kept at a well-controlled temperature undercontrolled pressure conditions to promote chemical reaction betweenthese molecular precursors, concurrent with efficient removal ofbyproducts. Obtaining optimum CVD performance requires the ability toachieve and sustain steady-state conditions of gas flow, temperature,and pressure throughout the process, and the ability to minimize oreliminate transients.

Especially in the field of semiconductor, integrated circuit, and otherelectronic devices, there is a demand for thin films, especially higherquality, denser films, with superior conformal coating properties,beyond the achievable limits of conventional CVD techniques, especiallythin films that can be manufactured at lower temperatures.

Atomic layer deposition (“ALD”) is an alternative film depositiontechnology that can provide improved thickness resolution and conformalcapabilities, compared to its CVD predecessor. The ALD process segmentsthe conventional thin-film deposition process of conventional CVD intosingle atomic-layer deposition steps. Advantageously, ALD steps areself-terminating and can deposit one atomic layer when conducted up toor beyond self-termination exposure times. An atomic layer typicallyranges from about 0.1 to about 0.5 molecular monolayers, with typicaldimensions on the order of no more than a few Angstroms. In ALD,deposition of an atomic layer is the outcome of a chemical reactionbetween a reactive molecular precursor and the substrate. In eachseparate ALD reaction-deposition step, the net reaction deposits thedesired atomic layer and substantially eliminates “extra” atomsoriginally included in the molecular precursor. In its most pure form,ALD involves the adsorption and reaction of each of the precursors inthe absence of the other precursor or precursors of the reaction. Inpractice, in any system it is difficult to avoid some direct reaction ofthe different precursors leading to a small amount of chemical vapordeposition reaction. The goal of any system claiming to perform ALD isto obtain device performance and attributes commensurate with an ALDsystem while recognizing that a small amount of CVD reaction can betolerated.

In ALD applications, typically two molecular precursors are introducedinto the ALD reactor in separate stages. For example, a metal precursormolecule, ML_(x), comprises a metal element, M that is bonded to anatomic or molecular ligand, L. For example, M could be, but would not berestricted to, Al, W, Ta, Si, Zn, etc. The metal precursor reacts withthe substrate when the substrate surface is prepared to react directlywith the molecular precursor. For example, the substrate surfacetypically is prepared to include hydrogen-containing ligands, AH or thelike, that are reactive with the metal precursor. Sulfur (S), oxygen(O), and Nitrogen (N) are some typical A species. The gaseous metalprecursor molecule effectively reacts with all of the ligands on thesubstrate surface, resulting in deposition of a single atomic layer ofthe metal:substrate−AH+ML _(x)→substrate−AML _(x-1) +HL  (1)where HL is a reaction by-product. During the reaction, the initialsurface ligands, AH, are consumed, and the surface becomes covered withL ligands, which cannot further react with metal precursor ML_(x).Therefore, the reaction self-terminates when all of the initial AHligand is on the surface are replaced with AML_(x-1) species. Thereaction stage is typically followed by an inert-gas purge stage thateliminates the excess metal precursor from the chamber prior to theseparate introduction of a second reactant gaseous precursor material.

The second molecular precursor then is used to restore the surfacereactivity of the substrate towards the metal precursor. This is done,for example, by removing the L ligands and redepositing AH ligands. Inthis case, the second precursor typically comprises the desired (usuallynonmetallic) element A (i.e., O, N, S), and hydrogen (i.e., H₂O, NH₃,H₂S). The next reaction is as follows:substrate−A−ML+AH _(Y)→substrate−A−M−AH+HL  (2)This converts the surface back to its AH-covered state. (Here, for thesake of simplicity, the chemical reactions are not balanced.) Thedesired additional element, A, is incorporated into the film and theundesired ligands, L, are eliminated as volatile by-products. Onceagain, the reaction consumes the reactive sites (this time, the Lterminated sites) and self-terminates when the reactive sites on thesubstrate are entirely depleted. The second molecular precursor then isremoved from the deposition chamber by flowing inert purge-gas in asecond purge stage.

In summary, then, the basic ALD process requires alternating, insequence, the flux of chemicals to the substrate. The representative ALDprocess, as discussed above, is a cycle having four differentoperational stages:

1. ML_(x) reaction;

2. ML_(x) purge;

3. AH_(y) reaction; and

4. AH_(y) purge, and then back to stage 1.

This repeated sequence of alternating surface reactions andprecursor-removal that restores the substrate surface to its initialreactive state, with intervening purge operations, is a typical ALDdeposition cycle. A key feature of ALD operation is the restoration ofthe substrate to its initial surface chemistry condition. Using thisrepeated set of steps, a film can be layered onto the substrate in equalmetered layers that are all alike in chemical kinetics, deposition percycle, composition, and thickness.

ALD can be used as a fabrication step for forming a number of types ofthin-film electronic devices, including semiconductor devices andsupporting electronic components such as resistors and capacitors,insulators, bus lines and other conductive structures. ALD isparticularly suited for forming thin layers of metal oxides in thecomponents of electronic devices. General classes of functionalmaterials that can be deposited with ALD include conductors, dielectricsor insulators, and semiconductors.

Conductors can be any useful conductive material. For example, theconductors may comprise transparent materials such as indium-tin oxide(ITO), doped zinc oxide ZnO, SnO₂, or In₂O₃. The thickness of theconductor may vary, and according to particular examples it can rangefrom about 50 to about 1000 nm.

Examples of useful semiconducting materials are compound semiconductorssuch as gallium arsenide, gallium nitride, cadmium sulfide, intrinsiczinc oxide, and zinc sulfide.

A dielectric material electrically insulates various portions of apatterned circuit. A dielectric layer may also be referred to as aninsulator or insulating layer. Specific examples of materials useful asdielectrics include strontiates, tantalates, titanates, zirconates,aluminum oxides, silicon oxides, tantalum oxides, hafnium oxides,titanium oxides, zinc selenide, and zinc sulfide. In addition, alloys,combinations, and multilayers of these examples can be used asdielectrics. Of these materials, aluminum oxides are preferred.

A dielectric structure layer may comprise two or more layers havingdifferent dielectric constants. Such insulators are discussed in U.S.Pat. No. 5,981,970 hereby incorporated by reference and copending U.S.application Ser. No. 11/088,645, hereby incorporated by reference.Dielectric materials typically exhibit a band-gap of greater than about5 eV. The thickness of a useful dielectric layer may vary, and accordingto particular examples it can range from about 10 to about 300 nm.

A number of device structures can be made with the functional layersdescribed above. A resistor can be fabricated by selecting a conductingmaterial with moderate to poor conductivity. A capacitor can be made byplacing a dielectric between two conductors. A diode can be made byplacing two semiconductors of complementary carrier type between twoconducting electrodes. There may also be disposed between thesemiconductors of complementary carrier type a semiconductor region thatis intrinsic, indicating that that region has low numbers of free chargecarriers. A diode may also be constructed by placing a singlesemiconductor between two conductors, where one of theconductor/semiconductors interfaces produces a Schottky barrier thatimpedes current flow strongly in one direction. A transistor may be madeby placing upon a conductor (the gate) an insulating layer followed by asemiconducting layer. If two or more additional conductor electrodes(source and drain) are placed spaced apart in contact with the topsemiconductor layer, a transistor can be formed. Any of the abovedevices can be created in various configurations as long as thenecessary interfaces are created.

In typical applications of a thin film transistor, the need is for aswitch that can control the flow of current through the device. As such,it is desired that when the switch is turned on a high current can flowthrough the device. The extent of current flow is related to thesemiconductor charge carrier mobility. When the device is turned off, itis desirable that the current flow be very small. This is related to thecharge carrier concentration. Furthermore, it is generally preferablethat visible light have little or no influence on thin-film transistorresponse. In order for this to be true, the semiconductor band gap mustbe sufficiently large (>3 eV) so that exposure to visible light does notcause an inter-band transition. A material that is capable of yielding ahigh mobility, low carrier concentration, and high band gap is ZnO.Furthermore, for high-volume manufacture onto a moving web, it is highlydesirable that chemistries used in the process be both inexpensive andof low toxicity, which can be satisfied by the use of ZnO and themajority of its precursors.

Self-saturating surface reactions make ALD relatively insensitive totransport non-uniformities, which might otherwise impair surfaceuniformity, due to engineering tolerances and the limitations of theflow system or related to surface topography (that is, deposition intothree dimensional, high aspect ratio structures). As a general rule, anon-uniform flux of chemicals in a reactive process generally results indifferent completion times over different portions of the surface area.However, with ALD, each of the reactions is allowed to complete on theentire substrate surface. Thus, differences in completion kineticsimpose no penalty on uniformity. This is because the areas that arefirst to complete the reaction self-terminate the reaction; other areasare able to continue until the full treated surface undergoes theintended reaction.

Typically, an ALD process deposits about 0.1-0.2 nm of a film in asingle ALD cycle (with one cycle having numbered steps 1 through 4 aslisted earlier). A useful and economically feasible cycle time must beachieved in order to provide a uniform film thickness in a range ofabout from 3 nm to 30 nm for many or most semiconductor applications,and even thicker films for other applications. According to industrythroughput standards, substrates are preferably processed within 2minutes to 3 minutes, which means that ALD cycle times must be in arange from about 0.6 seconds to about 6 seconds.

ALD offers considerable promise for providing a controlled level ofhighly uniform thin film deposition. However, in spite of its inherenttechnical capabilities and advantages, a number of technical hurdlesstill remain. One important consideration relates to the number ofcycles needed. Because of its repeated reactant and purge cycles,effective use of ALD has required an apparatus that is capable ofabruptly changing the flux of chemicals from ML_(x) to AH_(y), alongwith quickly performing purge cycles. Conventional ALD systems aredesigned to rapidly cycle the different gaseous substances onto thesubstrate in the needed sequence. However, it is difficult to obtain areliable scheme for introducing the needed series of gaseousformulations into a chamber at the needed speeds and without someunwanted mixing. Furthermore, an ALD apparatus must be able to executethis rapid sequencing efficiently and reliably for many cycles in orderto allow cost-effective coating of many substrates.

In an effort to minimize the time that an ALD reaction needs to reachself-termination, at any given reaction temperature, one approach hasbeen to maximize the flux of chemicals flowing into the ALD reactor,using so-called “pulsing” systems. In order to maximize the flux ofchemicals into the ALD reactor, it is advantageous to introduce themolecular precursors into the ALD reactor with minimum dilution of inertgas and at high pressures. However, these measures work against the needto achieve short cycle times and the rapid removal of these molecularprecursors from the ALD reactor. Rapid removal in turn dictates that gasresidence time in the ALD reactor be minimized. Gas residence times, τ,are proportional to the volume of the reactor, V, the pressure, P, inthe ALD reactor, and the inverse of the flow, Q, that is:τ=VP/Q  (3)

In a typical ALD chamber, the volume (V) and pressure (P) are dictatedindependently by the mechanical and pumping constraints, leading todifficulty in precisely controlling the residence time to low values.Accordingly, lowering pressure (P) in the ALD reactor facilitates lowgas residence times and increases the speed of removal (purge) ofchemical precursor from the ALD reactor. In contrast, minimizing the ALDreaction time requires maximizing the flux of chemical precursors intothe ALD reactor through the use of a high pressure within the ALDreactor. In addition, both gas residence time and chemical usageefficiency are inversely proportional to the flow. Thus, while loweringflow can increase efficiency, it also increases gas residence time.

Existing ALD approaches have been compromised with the trade-off betweenthe need to shorten reaction times with improved chemical utilizationefficiency, and, on the other hand, the need to minimize purge-gasresidence and chemical removal times. One approach to overcome theinherent limitations of “pulsed” delivery of gaseous material is toprovide each reactant gas continuously and to move the substrate througheach gas in succession. For example, U.S. Pat. No. 6,821,563 entitled“GAS DISTRIBUTION SYSTEM FOR CYCLICAL LAYER DEPOSITION” to Yudovskydescribes a processing chamber, under vacuum, having separate gas portsfor precursor and purge gases, alternating with vacuum pump portsbetween each gas port. Each gas port directs its stream of gasvertically downward toward a substrate. The separate gas flows areseparated by walls or partitions, with vacuum, pumps for evacuating gason both sides of each gas stream. A lower portion of each partitionextends close to the substrate, for example, about 0.5 mm or greaterfrom the substrate surface. In this manner, the lower portions of thepartitions are separated from the substrate surface by a distancesufficient to allow the gas streams to flow around the lower portionstoward the vacuum ports after the gas streams react with the substratesurface.

A rotary turntable or other transport device is provided for holding oneor more substrate wafers. With this arrangement, the substrate isshuttled beneath the different gas streams, effecting ALD depositionthereby. In one embodiment, the substrate is moved in a linear paththrough a chamber, in which the substrate is passed back and forth anumber of times.

Another approach using continuous gas flow is shown in U.S. Pat. No.4,413,022 entitled “METHOD FOR PERFORMING GROWTH OF COMPOUND THIN FILMS”to Suntola et al. A gas flow array is provided with alternating sourcegas openings, carrier gas openings, and vacuum exhaust openings.Reciprocating motion of the substrate over the array effects ALDdeposition, again, without the need for pulsed operation. In theembodiment of FIGS. 13 and 14, in particular, sequential interactionsbetween a substrate surface and reactive vapors are made by areciprocating motion of the substrate over a fixed array of sourceopenings. Diffusion barriers are formed by having a carrier gas openingbetween exhaust openings. Suntola et al. state that operation with suchan embodiment is possible even at atmospheric pressure, although littleor no details of the process, or examples, are provided.

While systems such as those described in the '563 Yudovsky and '022Suntola et al. disclosures may avoid some of the difficulties inherentto pulsed gas approaches, these systems have other drawbacks. Neitherthe gas flow delivery unit of the '563 Yudovsky disclosure nor the gasflow array of the '022 Suntola et al. disclosure can be used in closerproximity to the substrate than about 0.5 mm. Neither of the gas flowdelivery apparatus disclosed in the '563 Yudovsky and '022 Suntola etal. patents are arranged for possible use with a moving web surface,such as could be used as a flexible substrate for forming electroniccircuits, light sensors, or displays, for example. The complexarrangements of both the gas flow delivery unit of the '563 Yudovskydisclosure and the gas flow array of the '022 Suntola et al. disclosure,each providing both gas flow and vacuum, make these solutions difficultto implement and costly to scale and limit their potential usability todeposition applications onto a moving substrate of limited dimensions.Moreover, it would be very difficult to maintain a uniform vacuum atdifferent points in an array and to maintain synchronous gas flow andvacuum at complementary pressures, thus compromising the uniformity ofgas flux that is provided to the substrate surface.

U.S. patent Pub. No. 2005/0084610 to Selitser discloses an atmosphericpressure atomic layer chemical vapor deposition process. Selitser et al.state that extraordinary increases in reaction rates are obtained bychanging the operating pressure to atmospheric pressure, which willinvolve orders of magnitude increase in the concentration of reactants,with consequent enhancement of surface reactant rates. The embodimentsof Selitser et al. involve separate chambers for each stage of theprocess, although FIG. 10 in 2005/0084610 shows an embodiment in whichchamber walls are removed. A series of separated injectors are spacedaround a rotating circular substrate holder track. Each injectorincorporates independently operated reactant, purging, and exhaust gasmanifolds and controls and acts as one complete mono-layer depositionand reactant purge cycle for each substrate as is passes there under inthe process. Little or no specific details of the gas injectors ormanifolds are described by Selitser et al., although they state thatspacing of the injectors is selected so that cross-contamination fromadjacent injectors is prevented by purging gas flows and exhaustmanifolds incorporate in each injector.

Typical diffuser systems for gases will diffuse gases isotropically.Considering the design of a coating head, that may be beneficial byproviding flow uniformity. In an ALD system such as in '563 Yudovsky,however, such diffusion would allow gases to diffuse laterally, whichwould disadvantageously cause reaction between neighboring gas streams.

ALD processing devices such as described above and the transverse-flowALD device of the above-cited U.S. Ser. No. 11/392,006 and thefloating-head ALD device of the above-cited U.S. Ser. No. 11/620,738 allprovide for the spatial separation of mutually reactive gases. Theefficiency of these devices is further improved by placing these gasesin relatively close proximity, but still not allowing them to mix dueone or more of factors such as the presence of purge streams, and theuse of particular flow patterns. When attempting to have these gases inclose proximity, it is important to deliver gases is a relativelyprecise way, with good uniformity over the dimensions of a deliveryhead.

OBJECT OF THE INVENTION

An object of the present invention is, when placing reactive gases inclose proximity in an ALD coating process, to deliver gases in arelatively precise way, with good uniformity over the dimensions of adelivery head.

Another object of the present invention is to diffuse the gases whilemaintaining channel separation during simultaneous gas flow.

Another object is, in providing this uniformity, to produce a uniformbackpressure over an extended area of an output channel, thus diffusingthe flow of the gas.

Another object is to provide efficient and easy-to-assemble diffusersystems for a delivery head.

Another object is to provide an ALD deposition method and apparatus thatcan be used with a continuous process and that can provide improved gasflow separation over earlier solutions.

Another object is to provide an ALD deposition method and apparatus thatis more robust to potential disturbances or irregularities in processconditions or circumstances during operation.

Another object is to provide, in embodiments that use a floatingdelivery head, an ALD deposition method and apparatus thatadvantageously provides improved mobility.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and process for depositing athin film material on a substrate, comprising simultaneously directing aseries of gas flows from the output face of a delivery head of a thinfilm deposition system toward the surface of a substrate, wherein theseries of gas flows comprises at least a first reactive gaseousmaterial, an inert purge gas, and a second reactive gaseous material.The first reactive gaseous material is capable of reacting with asubstrate surface treated with the second reactive gaseous material. Inparticular, the present invention relates to a delivery device forthin-film material deposition onto a substrate comprising:

A delivery device for thin-film material deposition onto a substratecomprising:

(a) a plurality of inlet ports comprising at least a first inlet port, asecond inlet port, and a third inlet port capable of receiving a commonsupply for a first gaseous material, a second gaseous material, and athird gaseous material, respectively;

(b) at least one exhaust port capable of receiving exhaust gas fromthin-film material deposition and at least two elongated exhaustchannels, each of the elongated exhaust channels capable of gaseousfluid communication with the at least one exhaust port;

(c) at least three groups of elongated emissive channels, (i) a firstgroup comprising one or more first elongated emissive channels, (ii) asecond group comprising one or more second elongated emissive channels,and (iii) a third group comprising at least two third elongated emissivechannels, each of the first, second, and third elongated emissivechannels capable of gaseous fluid communication, respectively, with oneof the corresponding first inlet port, second inlet port, and thirdinlet port;

wherein each of the first, second, and third elongated emissive channelsand each of the elongated exhaust channels extend in a length directionsubstantially in parallel;

wherein each first elongated emissive channel is separated on at leastone elongated side thereof from a nearest second elongated emissivechannel by a relatively nearer elongated exhaust channel and arelatively less near third elongated emissive channel;

wherein each first elongated emissive channel and each second elongatedemissive channel is situated between relatively nearer elongated exhaustchannels and between relatively less nearer elongated emissive channels;and

(d) a gas diffuser associated with at least one group of the threegroups of elongated emissive channels such that at least one of thefirst, second, and third gaseous material, respectively, is capable ofpassing through the gas diffuser prior to delivery from the deliverydevice to the substrate, during thin-film material deposition onto thesubstrate, and wherein the gas diffuser maintains flow isolation of theat least one of first, second, and third gaseous material downstreamfrom each of the elongated emissive channels in the at least one groupof elongated emissive channels.

Thus, the delivery device can comprise a single first elongated emissivechannel, a single second elongated emissive channel, and two or morethird elongated emissive channels, although a plurality (two or more) ofeach are preferred, as described below. Accordingly the term “group” cancomprise a single member.

Preferably, the delivery head comprises a plurality of first elongatedemissive channels and/or a plurality of second elongated emissivechannels for various applications. However, as a minimum, a one-stagedelivery head can have, for example, only one metal and or one oxidizerchannel in combination with at least two purge channels. A plurality ofindividual “delivery-head sub-units”that are connected together, or thatare transported in sync during thin-film deposition onto a substrate, orthat treat the same substrate during a common period of time areconsidered a “delivery head” for the purpose of the present invention,even though separately constructed or separable after deposition.

In a preferred embodiment, the first and second gaseous materials can bemutually reactive gases, and the third gaseous material can be a purgegas such as nitrogen.

In one particularly advantageous aspect of the invention, the gasdiffuser is capable of providing a friction factor that is greater than1×10², assuming a representative gas that is nitrogen at 25° C. and arepresentative average velocity between 0.01 and 0.5 m/sec of gaseousmaterial passing through the gas diffuser.

In one embodiment of the invention, the gas diffuser comprises a porousmaterial through which the at least one of the first, second, and thirdgaseous material passes.

In a second embodiment of the invention, the gas diffuser comprises amechanically formed assembly comprising at least two elements, eachcomprising a substantially parallel surface area facing each other, eachelement comprising interconnected passages each in fluid communicationwith one of the individual elongated emissive channels among the atleast one group of elongated emissive channels, wherein the gas diffuserdeflects gaseous material passing therethough by providing twosubstantially vertical flow paths for gaseous material separated by asubstantially horizontal flow path for gaseous material, wherein thesubstantially vertical flow path is provided by one or more passagesextending in an elongated direction and wherein the substantiallyhorizontal flow path is provided by a thin space between the parallelsurface areas in the two elements, wherein vertical refers to theorthogonal direction with respect to the output face of the deliverydevice.

In a preferred embodiment, the gas diffuser is associated with each ofthe three groups of elongated emissive channels such that each of thefirs, second, and third gaseous material, respectively, is capable ofseparately passing from the delivery device to the substrate duringthin-film material deposition on the substrate, and wherein the gasdiffuser maintains flow isolation of each of first, second, and thirdgaseous material downstream from each of the elongated emissive channelsin the three groups of elongated emissive channels.

Another aspect of the present invention relates to a deposition systemwherein the above-described delivery device is capable of providing thinfilm deposition of a solid material onto a substrate in a system inwhich a substantially uniform distance is maintained between the outputface of the delivery head and the substrate surface during thin filmdeposition.

Yet another aspect of the present invention relates to a process fordepositing a thin film material on a substrate, comprisingsimultaneously directing a series of gas flows from the output face of adelivery head toward the surface of a substrate, wherein the series ofgas flows comprises at least a first reactive gaseous material, an inertpurge gas, and a second reactive gaseous material, and wherein the firstreactive gaseous material is capable of reacting with a substratesurface treated with the second reactive gaseous material. The deliveryhead comprises a gas diffuser element through which passes at least oneof (preferably all three of) the first reactive gaseous material, theinert purge gas, and the second reactive gaseous material whilemaintaining flow isolation of the at one gaseous material.Advantageously, the gas diffuser provides a friction factor for gaseousmaterial passing therethrough that is greater than 1×10², therebyproviding back pressure and promoting equalization of pressure where theflow of the at least one first, second and third gaseous material exitsthe delivery device.

The friction factor assumes that the characteristic friction factor areais equal to the entire area between exhaust elongated channels on eitherside of each emissive elongated channel of said at least one group ofemissive elongated channels, thereby providing back pressure andpromoting the equalization of pressure where the flow of the at leastone first, second and third gaseous material exits the delivery device.

In one preferred embodiment, one or more of the gas flows provides apressure that at least contributes to the separation of the surface ofthe substrate from the face of the delivery head.

In another embodiment, the system provides a relative oscillating motionbetween the distribution head and the substrate. In a preferredembodiment, the system can be operated with continuous movement of asubstrate being subjected to thin film deposition, wherein the system iscapable of conveying the support on or as a web past the distributionhead, preferably in an unsealed environment to ambient at substantiallyatmospheric pressure.

It is an advantage of the present invention that it can provide acompact apparatus for atomic layer deposition onto a substrate that iswell suited to a number of different types of substrates and depositionenvironments.

It is a further advantage of the present invention that it allowsoperation, in preferred embodiments, under atmospheric pressureconditions.

It is yet a further advantage of the present invention that it isadaptable for deposition on a web or other moving substrate, includingdeposition onto a large area substrate.

It is still a further advantage of the present invention that it can beemployed in low temperature processes at atmospheric pressures, whichprocess may be practice in an unsealed environment, open to ambientatmosphere. The method of the present invention allows control of thegas residence time τ in the relationship shown earlier in equation (3),allowing residence time τ to be reduced, with system pressure and volumecontrolled by a single variable, the gas flow.

As used herein, the terms “vertical,” “horizontal,” “top,” “bottom,”“front,” “back,” or “parallel,” and the like, unless otherwiseindicated, are with reference to a front/bottom horizontal face of thedelivery device or a top horizontal parallel surface of the substratebeing treated, in an theoretical configuration in which the deliveryhead is vertically over the substrate, although that configuration isoptional, for example, the substrate can be positioned over the face ofthe delivery head or otherwise positioned.

These and other objects, features, and advantages of the presentinvention will become apparent to those skilled in the art upon areading of the following detailed description when taken in conjunctionwith the drawings wherein there is shown and described an illustrativeembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter of the present invention, itis believed that the invention will be better understood from thefollowing description when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a cross-sectional side view of one embodiment of adistribution manifold for atomic layer deposition according to thepresent invention;

FIG. 2 is a cross-sectional side view of one embodiment of a deliveryhead showing one exemplary arrangement of gaseous materials provided toa substrate that is subject to thin film deposition;

FIGS. 3A and 3B are cross-sectional side views of one embodiment of adistribution manifold, schematically showing the accompanying depositionoperation;

FIG. 4 is a perspective exploded view of a delivery head in a depositionsystem according including a diffuser unit according to one embodimentof the present invention;

FIG. 5A is a perspective view of a connection plate for the deliveryhead of FIG. 4;

FIG. 5B is a plan view of a gas chamber plate for the delivery head ofFIG. 4;

FIG. 5C is a plan view of a gas direction plate for the delivery head ofFIG. 4;

FIG. 5D is a plan view of a base plate for the delivery head of FIG. 4;

FIG. 6 is a perspective view showing a base plate on a delivery head inone embodiment;

FIG. 7 is an exploded view of a gas diffuser unit according to oneembodiment;

FIG. 8A is a plan view of a nozzle plate of the gas diffuser unit ofFIG. 7;

FIG. 8B is a plan view of a gas diffuser plate of the gas diffuser unitof FIG. 7;

FIG. 8C is a plan view of a face plate of the gas diffuser unit of FIG.7;

FIG. 8D is a perspective view of gas mixing within the gas diffuser unitof FIG. 7;

FIG. 8E is a perspective view of the gas ventilation path using the gasdiffuser unit of FIG. 7;

FIG. 9A is a perspective view of a portion of the delivery head in anembodiment using vertically stacked plates;

FIG. 9B is an exploded view of the components of the delivery head shownin FIG. 9A;

FIG. 9C is a plan view showing a delivery assembly formed using stackedplates;

FIGS. 10A and 10B are plan and perspective views, respectively, of aseparator plate used in the vertical plate embodiment of FIG. 9A;

FIGS. 11A and 11B are plan and perspective views, respectively, of apurge plate used in the vertical plate embodiment of FIG. 9A;

FIGS. 12A and 12B are plan and perspective views, respectively, of anexhaust plate used in the vertical plate embodiment of FIG. 9A;

FIGS. 13A and 13B are plan and perspective views, respectively, of areactant plate used in the vertical plate embodiment of FIG. 9A;

FIG. 13C is a plan view of a reactant plate in an alternate orientation;

FIG. 14 is a side view of one embodiment of a deposition systemcomprising a floating delivery head and showing relevant distancedimensions and force directions;

FIG. 15 is a perspective view showing a distribution head used with asubstrate transport system;

FIG. 16 is a perspective view showing a deposition system using thedelivery head of the present invention;

FIG. 17 is a perspective view shoeing one embodiment of a depositionsystem applied to a moving web;

FIG. 18 is a perspective view showing another embodiment of depositionsystem applied to a moving web;

FIG. 19 is a cross-sectional side view of one embodiment of a deliveryhead with an output face having curvature;

FIG. 20 is a perspective view of an embodiment using a gas cushion toseparate the delivery head from the substrate; and

FIG. 21 is a side view showing embodiment for a deposition systemcomprising a gas fluid bearing for use with a moving substrate.

DETAILED DESCRIPTION OF THE INVENTION

The present description is directed in particular to elements formingpart of, or cooperating more directly with, apparatus in accordance withthe invention. It is to be understood that elements not specificallyshown or described may take various forms well known to those skilled inthe art.

For the description that follows, the term “gas” or “gaseous material”is used in a broad sense to encompass any of a range of vaporized orgaseous elements, compounds, or materials. Other terms used herein, suchas: “reactant,” “precursor,” “vacuum,” and “inert gas,” for example, allhave their conventional meanings as would be well understood by thoseskilled in the materials deposition art. The figures provided are notdrawn to scale but are intended to show overall function and thestructural arrangement of some embodiments of the present invention.Terms “upstream” and “downstream” have their conventional meanings asrelates to the direction of gas flow.

The apparatus of the present invention offers a significant departurefrom conventional approaches to ALD, employing an improved distributiondevice for delivery of gaseous materials to a substrate surface,adaptable to deposition on larger and web-based or web-supportedsubstrates and capable of achieving a highly uniform thin-filmdeposition at improved throughput speeds. The apparatus and method ofthe present invention employs a continuous (as opposed to pulsed)gaseous material distribution. The apparatus of the present inventionallows operation at atmospheric or near-atmospheric pressures as well asunder vacuum and is capable of operating in an unsealed or open-airenvironment.

Referring to FIG. 1, there is shown a cross-sectional side view of oneembodiment of a delivery head 10 for atomic layer deposition onto asubstrate 20 according to the present invention. Delivery head 10 has agas inlet conduit 14 that serves as an inlet port for accepting a firstgaseous material, a gas inlet conduit 16 for an inlet port that acceptsa second gaseous material, and a gas inlet conduit 18 for an inlet portthat accepts a third gaseous material. These gases are emitted at anoutput face 36 via, output channels 12, having a structural arrangementdescribed subsequently. The dashed-line arrows in FIG. 1 and subsequentFIGS. 2-3B refer to the delivery of gases to substrate 20 from deliveryhead 10. In FIG. 1, arrows X also indicate paths for gas exhaust (showndirected upwards in this figure) and exhaust channels 22, incommunication with an exhaust conduit 24 that provides an exhaust port.For simplicity of description, gas exhaust is not indicated in FIGS.2-3B. Because the exhaust gases still may contain quantities ofunreacted precursors, it may be undesirable to allow an exhaust flowpredominantly containing one reactive species to mix with onepredominantly containing another species. As such, it is recognized thatthe delivery head 10 may contain several independent exhaust ports.

In one embodiment, gas inlet conduits 14 and 16 are adapted to acceptfirst and second gases that react sequentially on the substrate surfaceto effect ALD deposition, and gas inlet conduit 18 receives a purge gasthat is inert with respect to the first and second gases. Delivery head10 is spaced a distance D from substrate 20, which may be provided on asubstrate support, as described in more detail subsequently.Reciprocating motion can be provided between substrate 20 and deliveryhead 10, either by movement of substrate 20, by movement of deliveryhead 10, or by movement of both substrate 20 and delivery head 10. Inthe particular embodiment shown in FIG. 1, substrate 20 is moved by asubstrate support 96 across output face 36 in reciprocating fashion, asindicated by the arrow A and by phantom outlines to the right and leftof substrate 20 in FIG. 1. It should be noted that reciprocating motionis not always required for thin-film deposition using delivery head 10.Other types of relative motion between substrate 20 and delivery head 10could also be provided, such as movement of either substrate 20 ordelivery head 10 in one or more directions, as described in more detailsubsequently.

The cross-sectional view of FIG. 2 shows gas flows emitted over aportion of output face 36 of delivery head 10 (with the exhaust pathomitted as noted earlier). In this particular arrangement, each outputchannel 12 is in gaseous flow communication with one of gas inletconduits 14, 16 or 18 seen in FIG. 1. Each output channel 12 deliverstypically a first reactant gaseous material O, or a second reactantgaseous material M, or a third inert gaseous material I.

FIG. 2 shows a relatively basic or simple arrangement of gases. It isenvisioned that a plurality of flows non-metal deposition precursors(like material O) or a plurality of flows metal-containing precursormaterials (like material M) may be delivered sequentially at variousports in a thin-film single deposition. Alternately, a mixture ofreactant gases, for example, a mixture of metal precursor materials or amixture of metal and non-metal precursors may be applied at a singleoutput channel when making complex thin film materials, for example,having alternate layers of metals or having lesser amounts of dopantsadmixed in a metal oxide material. Significantly, an inter-streamlabeled I for an inert gas, also termed a purge gas, separates anyreactant channels in which the gases are likely to react with eachother. First and second reactant gaseous materials O and M react witheach other to effect ALD deposition, but neither reactant gaseousmaterial O nor M reacts with inert gaseous material I. The nomenclatureused in FIG. 2 and following suggests some typical types of reactantgases. For example, first reactant gaseous material O could be anoxidizing gaseous material; second reactant gaseous material M would bea metal-containing compound, such as a material containing zinc. Inertgaseous material I could be nitrogen, argon, helium, or other gasescommonly used as purge gases in ALD systems. Inert gaseous material I isinert with respect to first or second reactant gaseous materials O andM. Reaction between first and second reactant gaseous materials wouldform a metal oxide or other binary compound, such as zinc oxide ZnO orZnS, used in semiconductors, in one embodiment. Reactions between morethan two reactant gaseous materials could form a ternary compound, forexample, ZnAlO.

The cross-sectional views of FIGS. 3A and 3B show, in simplifiedschematic form, the ALD coating operation performed as substrate 20passes along output face 36 of delivery head 10 when delivering reactantgaseous materials O and M. In FIG. 3A, the surface of substrate 20 firstreceives an oxidizing material continuously emitted from output channels12 designated as delivering first reactant gaseous material O. Thesurface of the substrate now contains a partially reacted form ofmaterial O, which is susceptible to reaction with material M. Then, assubstrate 20 passes into the path of the metal compound of secondreactant gaseous material M, the reaction with M takes place, forming ametallic oxide or some other thin film material that can be formed fromtwo reactant gaseous materials. Unlike conventional solutions, thedeposition sequence shown in FIGS. 3A and 3B is continuous duringdeposition for a given substrate or specified area thereof, rather thanpulsed. That is, materials O and M are continuously emitted as substrate20 passes across the surface of delivery head 10 or, conversely, asdelivery head 10 passes along the surface of substrate 20.

As FIGS. 3A and 3B show, inert gaseous material I is provided inalternate output channels 12, between the flows of first and secondreactant gaseous materials O and M. Notably, as was shown in FIG. 1,there are exhaust channels 22, but preferably no vacuum channelsinterspersed between the output channels 12. Only exhaust channels 22,providing a small amount of draw, are needed to vent spent gases emittedfrom delivery head 10 and used in processing.

In one embodiment, as described in more detail in copending, commonlyassigned U.S. Ser. No. 11/620,744, hereby incorporated by reference inits entirety, gas pressure is provided against substrate 20, such thatseparation distance D is maintained, at least in part, by the force ofpressure that is exerted. By maintaining some amount of gas pressurebetween output face 36 and the surface of substrate 20, the apparatus ofthe present invention provides at least some portion of an air bearing,or more properly a gas fluid bearing, for delivery head 10 itself or,alternately, for substrate 20. This arrangement helps to simplify thetransport requirements for delivery head 10, as described subsequently.The effect of allowing the delivery head to approach the substrate suchthat it is supported by gas pressure, helps to provide isolation betweenthe gas streams. By allowing the head to float on these streams,pressure fields are set up in the reactive and purge flow areas thatcause the gases to be directed from inlet to exhaust with little or nointermixing of other gas streams. In such a device, the close proximityof the coating head to the substrate leads to relatively high pressureand high variations of pressure under the head. The absence of a gasdiffuser system or an inadequate gas diffusion system within the headwould indicate that there is little pressure drop for gases flowingwithin the head. In such a case, if random forces cause a small increaseon the gap on one side of the head, the pressure in that area may belowered and gas may flow into that area in too high a proportion. Incontrast, when a diffuser system according to the present invention isused, the majority of pressure drop occurs inside the head, so that gasflow out of the head is maintained relatively uniformly despitepotential variations under the delivery head.

In one such embodiment, since the separation distance D is relativelysmall, even a small change in distance D (for example, even 100micrometers) would require a significant change in flow rates andconsequently gas pressure providing the separation distance D. Forexample, in one embodiment, doubling the separation distance D,involving a change less than 1 mm, would necessitate more than doubling,preferably more than quadrupling, the flow rate of the gases providingthe separation distance D. As a general principle, it is considered moreadvantageous in practice to minimize separation distance D and,consequently, to operate at reduced flow rates.

The present invention does not require a floating head system, however,and the delivery head and the substrate can be in at a fixed distance Das in conventional systems. For example, the delivery head and thesubstrate can be mechanically fixed at separation distance from eachother in which the head is not vertically mobile in relationship to thesubstrate in response to changes in flow rates and in which thesubstrate is on a vertically fixed substrate support.

In one embodiment, a delivery device having an output face for providinggaseous materials for thin-film material deposition onto a substratecomprises:

(a) a plurality of inlet ports comprising at least a first inlet port, asecond inlet port, and a third inlet port capable of receiving a commonsupply for a first gaseous material, a second gaseous material, and athird gaseous material, respectively; and

(b) at least three groups of elongated emissive channels, a first groupcomprising one or more first elongated emissive channels, a second groupcomprising one or more second elongated emissive channels, and a thirdgroup comprising at least two third elongated emissive channels, each ofthe first, second, and third elongated emissive channels allowinggaseous fluid communication with one of corresponding first inlet port,second inlet port, and third inlet port;

wherein each first elongated emissive channel is separated on at leastone elongated side thereof from the nearest second elongated emissivechannel by a third elongated emissive channel;

wherein each first elongated emissive channel and each second elongatedemissive channel is situated between third elongated emissive channels,

wherein each of the first, second, and third elongated emissive channelsextend in a length direction and are substantially in parallel;

wherein each of the elongated emissive channels in at least one group ofelongated emissive channels, of the three groups of elongated emissivechannels, is capable of directing a flow, respectively, of at least oneof the first gaseous material, second gaseous material, and the thirdgaseous material substantially orthogonally with respect to the outputface of the delivery device, which flow of gaseous material is capableof being provided, either directly or indirectly from each of theelongated emissive channels in the at least one group, substantiallyorthogonally to the surface of the substrate; and

wherein at least a portion of the delivery device is formed as aplurality of apertured plates, superposed to define a network ofinterconnecting supply chambers and directing channels for routing eachof the first, second, and third gaseous materials from its correspondinginlet port to its corresponding elongated emissive channels.

For example, the first and second gaseous materials can be mutuallyreactive gases, and the third gaseous material can be a purge gas.

The exploded view of FIG. 4 shows, for a small portion of the overallassembly in one embodiment, how delivery head 10 can be constructed froma set of apertured plates and shows an exemplary gas flow path for justone portion of one of the gases. A connection plate 100 for the deliveryhead 10 has a series of input ports 104 for connection to gas suppliesthat are upstream of delivery head 10 and not shown in FIG. 4. Eachinput port 104 is in communication with a directing chamber 102 thatdirects the received gas downstream to a gas chamber plate 110. Gaschamber plate 110 has a supply chamber 112 that is in gas flowcommunication with an individual directing channel 122 on a gasdirection plate 120. From directing channel 122, the gas flow proceedsto a particular elongated exhaust channel 134 on a base plate 130. A gasdiffuser unit 140 provides diffusion and final delivery of the input gasat its output face 36. An exemplary gas flow F1 is traced through eachof the component assemblies of delivery head 10. The x-y-z axisorientation shown in FIG. 4 also applies for FIGS. 5A and 7 in thepresent application.

As shown in the example of FIG. 4, delivery assembly 150 of deliveryhead 10 is formed as an arrangement of superposed apertured plates:connection plate 100, gas chamber plate 110, gas direction plate 120,and base plate 130. These plates are disposed substantially in parallelto output face 36 in this “horizontal” embodiment. Gas diffuser unit 140can also be formed from superposed apertured plates, as is describedsubsequently. It can be appreciated that any of the plates shown in FIG.4 could itself be fabrication from a stack of superposed plates. Forexample, it may be advantageous to form connection plate 100 from fouror five stacked apertured plates that are suitably coupled together.This type of arrangement can be less complex than machining or moldingmethods for forming directing chambers 102 and input ports 104.

As indicated above, the delivery device for thin-film materialdeposition onto a substrate comprises a gas diffuser, wherein thegaseous material from at least one (preferably all three) of a pluralityof elongated channels of said first, second, and third elongatedemissive channels is capable of passing through the gas diffuser priorto delivery from the delivery device to the substrate, includingdeposition onto the substrate, wherein the delivery device allows thepassage of each gaseous material in order through the respective inletport, elongated emissive channels, and (with respect to said at leastone plurality of emissive channels) gas diffuser. The gas diffuser canbe either in said at least one plurality of emissive elongated channelsand/or upstream of the emissive elongated channel.

In an advantageous embodiment, the gas diffuser is capable of providinga friction factor that is greater than 1×10², preferably 1×10⁴ to 1×10⁸,more preferably 1×10⁵ to 5×10⁶. This provides back pressure and promotesthe equalization of pressure where the flow of the at least one first,second and third gaseous material exits the delivery device.

This friction factor assumes that the characteristic area in theequation below is equal to the entire area between exhaust elongatedchannels on either side of each emissive elongated channel of said atleast one plurality of emissive elongated channels. In other words, thearea is defined by a straight line connected the two ends of therespective exhaust elongated channels. For the purpose of the apparatusclaims, this also assumes a representative gas that is nitrogen at 25°C. and an average velocity of between 0.01 and 0.5 m/sec, for thepurpose of calculating the friction factor for the apparatus apart froma method of use. The average velocity is calculated based on the flowrate divided by the characteristic area A defined below. (Theserepresentative values are for characterizing the delivery device apartfrom its method of use and do not apply to the process according to theinvention, in which actual values during the process apply.)

The term “friction factor” can be explained as follows. When a flow ofgas is passed through the channel, there will exist a higher pressure onthe upstream side of the diffuser than exists on the downstream side dueto the resistive nature of the diffuser. The difference in pressure isthe known as the pressure drop across the diffuser.

A gas diffuser according to the present invention (which can be anapparatus, material, or combination thereof) provides a resistance toflow in a channel, while still allowing fluid to pass uniformly. The gasdiffuser means such as used in this invention is placed at the end of aflow channel of some shape. In the absence of the gas diffuser, fluidcould leave the channel at any spot and would not be constrained toleave uniformly. With the gas diffuser present, fluid traveling up tothe gas diffuser will find a strong resistance there, and will travel bypath of least resistance along all areas of the diffuser to exitsubstantially more uniformly

Since the dominant property of the gas diffuser is its resistance toflow, it is convenient to characterize this resistance by accepted meansin the field of fluid dynamics (Transport Phenomena, R. B. Bird, W. E.Stewart, E. N Lightfoot, John Wiley & Sons, 1960, hereby incorporated byreference). Pressure drops across a diffuser can be characterized by thefriction factor, f, presented by the gas diffuser:

$\begin{matrix}{f = \frac{F_{k}}{A \times K}} & (4)\end{matrix}$

where F_(k) is the force exerted due to the fluid flow, ultimatelyrelated to the pressure drop, A is a characteristic area, and Krepresents the kinetic energy of the fluid flow. Diffusers can take manyshapes. For a typical system, as described for the present invention, Ais disposed perpendicular to the output flow and F_(k) is disposedparallel to the output flow. Thus, the term F_(k)/A can be taken as thepressure drop ΔP caused by the gas diffuser.

The kinetic energy term of the flow is:

$\begin{matrix}{K = {\frac{1}{2}\rho\left\langle v \right\rangle^{2}}} & (5)\end{matrix}$

where ρ is the gas density and <v> is the average velocity, equal to theflow rate of the gaseous material divided by the characteristic area A.(The density of nitrogen can be used for a first approximation for thegases actually used in the process, or as a representative gas forcharacterizing the delivery head apparatus.) Thus, the pressure drop dueto a gas diffuser can be reduced to:

$\begin{matrix}{{\Delta\; P} = {\frac{1}{2}f\;\rho\left\langle v \right\rangle^{2}}} & (6)\end{matrix}$

Equation (6) can be used to calculate the friction factor f adimensionless number, since the other factors can be experimentaldetermined or measured, as shown in the examples below.

Materials or devices exhibiting higher friction factors present a higherresistance to gas flow. The friction factor for a given diffuser can bemeasured by disposing the diffuser in some channel, and simultaneouslyrecording the pressure drop as well as the flow rate of gas presented tothe diffuser. From the flow rate of gas and knowledge of the shape ofthe channel, the velocity v can be calculated, thus allowing calculationof the friction factor from the above equation. The friction factor fora given system is not perfectly constant, but has some relatively weakdependence upon the flow rate. For practical purposes, it is onlyimportant that the friction factor be known at flow rates typical of usein a given system or method. With respect to a delivery head apparatus,apart from the method, the average velocity <v> can be taken as 0.01 to0.5 m/sec as a representative number. (The claimed friction factor inthe case of the apparatus should be met for all average velocities <v>in this representative range.)

A suitable gas diffuser is capable of providing a friction factor forgas flow through the gas diffuser that is greater than 1×10², preferably1×10⁴ to 1×10⁸, more preferably 1×10⁵ to 5×10⁶. This provides thedesired back pressure and promotes the equalization of pressure wherethe gas flow of the at least one first, second and third gaseousmaterial (preferably all three gaseous materials) exits the deliverydevice through the gas diffuser.

As indicated above, the characteristic area A for determining theaverage velocity <v> for equation (6) is equal to the entire areabetween exhaust elongated channels on either side of each individualemissive elongated channel among the emissive elongated channels in flowcommunication with the gas diffuser. In other words, the area is definedby a straight line connected the two ends of the respective exhaustelongated channels. For the purpose of the apparatus claims, this alsoassumes a representative gas that is nitrogen at 25° C.

The skilled artisan can appreciate that typical random materials byitself will not provide the necessary friction factor. For example, astainless steel perforated screen even though representing fairly smallfeatures for typical machined or mechanically fabricated elements, mayoffer a friction factor that is too low to be adequate by itself for thepresent gas diffuser, as shown in the Examples below.

For the purpose of determining the friction factor, in most cases, agood approximation can be made by using the pressure into the deliveryhead, since the effect of the flow path leading to the gas diffuser willbe relatively small.

The gas diffuser can be a mechanically formed apparatus that providesthe necessary friction factor, for example, wherein the emissiveelongated channels are designed to provide the first, second, and thirdgaseous material indirectly to the substrate after passing through a gasdiffuser element comprising openings in a solid material. For example,the solid material can be steel and the openings formed by molding,machining, the application of laser or lithography, or the like.

Alternatively, the gas diffuser can comprise a porous material. Insteadof machining holes in a solid material, a porous material having tinypores can be used to create the desired backpressure. The resultinguniform distribution of inlet gas allows improved uniformity ofdeposition growth as well as, for certain embodiments, better floatationof a floating head. Porous materials are advantageous for providing arelatively simple unit that avoids difficulty machining of steel and thelike.

In the literature, porous materials have been used to create backpressure for air bearings, but such applications are not concerned aboutcross-flow (i.e., gas moving laterally). Thus, sintered aluminaparticles might be used to form a membrane for an air bearing. In thepreferred embodiment of the ALD system of the present invention,however, gases preferably flow substantially vertically from the outlet,with minimal or no inadvertent sideways motion that could allow gasmixing. Therefore porous materials with substantially vertical tubularopenings or pores to direct the gas flow are especially desirable andadvantageous.

Porous materials have also been for filters, where the object is to keepone component of a flow on one side, while allowing another component topass through. In contrast, in the present invention, moderate resistanceto the flow of the entire gaseous material is the objective. For thispurpose, two preferred classes of porous materials are as follows:

A first preferred class of porous materials comprises porous materialswith uniform, controlled diameter, columnar-type pore structure. In amembrane (or layer) made of such material, flow through the membrane issubstantially uni-directional, essentially without any cross-flowbetween pore channels. Alumina formed by anodization of highly purealuminum is well-known in the literature for its uniformity of porediameter (though the cross-sectional shape of the pores is notnecessarily round or regular), and such materials are commerciallyavailable at diameters of 0.02, 0.1, and 0.2 microns. The pores inANOPORE alumina, a commercially available alumina, are fairly dense,1.23×10⁹ pores/cm² (J Chem Phys, V. 96, p. 7789, 1992). However, a widevariety of pore diameters and interpore distance can be fabricated.Porous materials can also be formed of titanium oxides, zirconiumoxides, and tin oxides (Adv. Materials, V. 13, p. 180, 2001). Anothercommercially available material with columnar pores is a PolycarbonateTrack Etch (PCTE) membrane, made from a thin, microporous polycarbonatefilm material, known as NUCLEOPORE. Block copolymers can form similarconfigurations, with a wide range of tunability.

Thus, in a preferred embodiment, the gas diffuser comprises porousmaterial comprises an isolating, non-connecting pores structure in whichpores are substantially vertical to the surface, for example, anodicalumina.

In all these materials, the precise range of pore diameter and densityof pores (or pore volume) must be adjusted to achieve the appropriatefriction factor for the flow required. It is desirable to avoidreactivity of the diffusing membrane with the flowing gases. This islikely to be less of a potential issue, for example, for inorganicoxides than for organic-based materials.

Furthermore, the membrane must have some mechanical toughness. Theflowing gases will exert pressure on the membranes. The toughness couldbe achieved by a support membrane, so that the friction factor isgenerated by a layer with smaller pores coupled with a more robust layerwith larger pores.

In a second preferred class of porous materials, porous materials arefabricated such that the flow can be isotropic, i.e. moving sidewaysinside the membrane, as well as through the membrane. However, forpresent purposes, such an isotropically-flowing material is preferablyseparated by walls on non-porous material (for example, ribs) thatisolate gaseous material in each output channel from gaseous material inother output channels and prevent gaseous materials from interminglingin the gas diffuser or when leaving the gas diffuser or delivery head.For example, such porous materials can be sintered from small particles,either organic or inorganic. Sintering typically involves applying heatand/or pressure, preferably both, sufficient to bond the particles. Awide variety of such porous materials are available commercially, suchas porous glass (VYCOR has, for example, having a void volume of 28%)and porous ceramics. Alternatively, fibrous materials can be compressedto create a tight network to limit or resist the flow of gas.Alternatively, porous stainless steel can be formed by plasma coatingonto a subsequently removed substrate.

In one embodiment, for producing suitable backpressure while stillproviding relative isolation between gas channels, polymeric materialstreated in a way to generate useful pores can be employed, for example,TEFLON material that is treated to produce porosity (GoreTex, Inc.;Newark, Del.). In this case, the pores may not be interconnected. Also,the natural chemical inertness of such materials is advantageous.

For porous materials that comprise pores formed from the interstitialspace between particles, pores that are interconnected voids in a solidmaterial formed by a voiding agent or other means, or pores that areformed from micro-scale or nano-scale fibers. For example, the porousmaterial can be formed from the interstitial space between inorganic ororganic particles which is held together by sintering, either bypressure and/or heat, adhesive material, or other bonding means.Alternatively, the porous material can result from the processing of apolymer film to generate porosity.

In a preferred embodiment, the gas diffuser comprises a porous materialthat comprise pores that are less than 10,000 nm in average diameter,preferably 10 to 5000 nm, more preferably 50 to 5000 nm in averagediameter, as determined by mercury intrusion porosity measurement.

Various configurations of the porous material in the gas diffuser arepossible. For example, the porous material can comprises one or morelayers of different porous materials or a layer of porous materialsupported by a porous or perforated sheet, which layers are optionallyseparated by spacer elements. Preferably, the porous material comprisesa layer that is 5 to 1000 micrometers thick, preferably 5 to 100micrometers thick, for example, about 60 μm. In one embodiment, theporous material is in the form of at least one horizontally disposedlayer that covers the face of the delivery assembly and comprises thepart of the delivery device from which the gaseous materials exits theoutput face.

The porous material can form a continuous layer, optionally withpassages mechanically formed therein. For example, the porous layer ofthe gas diffuser can comprise mechanically formed openings or elongatedchannels for the relatively unimpeded flow of exhaust gaseous materialback through the delivery device. Alternatively, the layer of porousmaterial can be in the form of a substantially completely continuousplate in a stack of plates.

In still another embodiment, the porous material can be introduced orformed inside elongated emissive channels or other walled channels inthe flow path from the elongated emissive channels, for example by thebonding or sintering of particles introduced into the channels. Channelscan be at least partially filled by porous material. For example, adiffuser element or portion thereof can be formed from elongatedchannels in a steel plate in which particles are introduced and thensintered.

Thus, the gas diffuser can be an assembly of elements in which porousmaterial is held in separate confined areas. For example, porous aluminamaterial can be grown onto a previously machined piece of aluminum sothat the resulting porous structure has big openings for purge channelsand sheets of vertical pores for the supply gases.

FIGS. 5A through 5D show each of the major components that are combinedtogether to form delivery head 10 in the embodiment of FIG. 4. FIG. 5Ais a perspective view of connection plate 100, showing multipledirecting chambers 102. FIG. 5B is a plan view of gas chamber plate 110.A supply chamber 113 is used for purge or inert gas for delivery head 10in one embodiment. A supply chamber 115 provides mixing for a precursorgas (O) in one embodiment; an exhaust chamber 116 provides an exhaustpath for this reactive gas. Similarly, a supply chamber 112 provides theother needed reactive gas, second reactant gaseous material (M); anexhaust chamber 114 provides an exhaust path for this gas.

FIG. 5C is a plan view of gas direction plate 120 for delivery head 10in this embodiment. Multiple directing channels 122, providing a secondreactant gaseous material (M), are arranged in a pattern for connectingthe appropriate supply chamber 112 with base plate 130. Correspondingexhaust directing channels 123 are positioned near directing channels122. Directing channels 90 provide the first reactant gaseous material(O) and have corresponding exhaust directing channels 91. Directingchannels 92 provide third inert gaseous material (I). Again, it must beemphasized that FIGS. 4 and 5A-5D show one illustrative embodiment;numerous other embodiments are also possible.

FIG. 5D is a plan view of base plate 130 for delivery head 10. Baseplate 130 has multiple elongated emissive channels 132 interleaved withelongated exhaust channels 134. Thus, in this embodiment, there are atleast two elongated second emissive channels and each first elongatedemissive channel is separated on both elongated sides thereof from thenearest second elongated emissive channel by firstly an elongatedexhaust channel and secondly a third elongated emissive channel. Moreparticularly there are a plurality of second elongated emissive channelsand a plurality of first elongated emissive channels; wherein each firstelongated emissive channel is separated on both elongated sides thereoffrom the nearest second elongated emissive channel by firstly anelongated exhaust channel and secondly a third elongated emissivechannel; and wherein each second elongated emissive channel is separatedon both elongated sides thereof from the nearest first elongatedemissive channel by firstly an elongated exhaust channel and secondlythird elongated emissive channel. Obviously, the delivery device cannevertheless comprise a first or second elongated emissive channel ateach of two ends of the delivery head that does not have a second orfirst elongated emissive channel, respectively, on the side closest toan edge (the upper and lower edge in FIG. 5D) of the output face of thedelivery device.

FIG. 6 is a perspective view showing base plate 130 formed fromhorizontal plates and showing input ports 104. The perspective view ofFIG. 6 shows the external surface of base plate 130 as viewed from theoutput side and having elongated emissive channels 132 and elongatedexhaust channels 134. With reference to FIG. 4, the view of FIG. 6 istaken from the side that faces the direction of the substrate.

The exploded view of FIG. 7 shows the basic arrangement of componentsused to form one embodiment of a mechanical gas diffuser unit 140, asused in the embodiment of FIG. 4 and in other embodiments as describedsubsequently. These include a nozzle plate 142, shown in the plan viewof FIG. 8A. As shown in the plan view of FIG. 8A, nozzle plate 142mounts against base plate 130 and obtains its gas flows from elongatedemissive channels 132. In the embodiment shown, first diffuser outputpassage 143 in the form of nozzle holes provide the needed gaseousmaterials. Slots 180 are provided in the exhaust path, as describedsubsequently.

A gas diffuser plate 146, which diffuses in cooperation with nozzleplate 142 and face plate 148, shown in FIG. 8B, is mounted againstnozzle plate 142. The arrangement of the various passages on nozzleplate 142, gas diffuser plate 146, and face plate 148 are optimized toprovide the needed amount of diffusion for the gas flow and, at the sametime, to efficiently direct exhaust gases away from the surface area ofsubstrate 20. Slots 182 provide exhaust ports. In the embodiment shown,gas supply slots forming second diffuser output passage 147 and exhaustslots 182 alternate in gas diffuser plate 146.

A face plate 148, as shown in FIG. 8C, then faces substrate 20. Thirddiffuser passage 149 for providing gases and exhaust slots 184 againalternate with this embodiment.

FIG. 8D focuses on the gas delivery path through gas diffuser unit 140;FIG. 8E then shows the gas exhaust path in a corresponding manner.Referring to FIG. 8D there is shown, for a representative set of gasports, the overall arrangement used for thorough diffusion of thereactant gas for an output flow F2 in one embodiment. The gas from baseplate 130 (FIG. 4) is provided through first diffuser passage 143 onnozzle plate 142. The gas goes downstream to second diffuser passage 147on gas diffuser plate 146. As shown in FIG. 8D, there can be a verticaloffset (that is, using the horizontal plate arrangement shown in FIG. 7,vertical being normal with respect to the plane of the horizontalplates) between passages 143 and 147 in one embodiment, helping togenerate backpressure and thus facilitate a more uniform flow. The gasthen goes further downstream to third diffuser passage 149 on face plate148 to provide output channel 12. The different diffuser passages 143,147 and 149 may not only be spatially offset, but may also havedifferent geometries to contribute to intermolecular mixing andhomogenous diffusion of the gaseous materials when flowing through thedelivery head.

In the particular case of the arrangement of FIG. 8D, the majority ofthe backpressure is generated by the nozzle holes forming passage 143.If this gas is directed without the subsequent passages 147 and 149 tothe substrate, the high velocity of the gas coming out of the nozzleholes may cause non-uniformities. Thus passages 147 and 149 help toimprove uniformity of the gas flow. Alternatively, a coating device canoperate with only a nozzle based back-pressure generator, thuseliminating passages 147 and 149, at the expense of slight coatingnon-uniformities.

The nozzle holes in the nozzle plate 142 can be of any size suitable forback-pressure generation. These holes are preferably less than 200microns, more preferably less than 100 microns in diameter on average.Furthermore, the use of holes in the back-pressure generator isconvenient but not necessary. The back pressure can also be generated byother geometries such as a slit, as long as the size is chosen toprovide the desired back pressure.

FIG. 8E symbolically traces the exhaust path provided for venting gasesin a similar embodiment, where the downstream direction is opposite thatfor supplied gases. A flow F3 indicates the path of vented gases throughsequential third, second, and first exhaust slots 184, 182, and 180,respectively. Unlike the more circuitous mixing path of flow F2 for gassupply, the venting arrangement shown in FIG. 8E is intended for therapid movement of spent gases from the surface. Thus, flow F3 isrelatively direct, venting gases away from the substrate surface.

Thus, in the embodiment of FIG. 7, the gaseous material from each of theindividual elongated emissive channels among the first, second, andthird elongated emissive channels 132 is capable of separately passingthrough the gas diffuser unit 140 prior to delivery from the deliverydevice to the substrate, wherein the delivery device allows the passageof each gaseous material, in order, through the respective inlet port,elongated emissive channels, and gas diffuser unit 140. The gas diffuserunit in this embodiment is gas diffuser means for each of the threegaseous materials, although separate or isolated diffuser elements canbe used that do not form a common assembly. Diffuser elements can alsobe associated with, or placed in, the exhaust channels.

In this embodiment, also, the gas diffuser unit 140 is a unit isdesigned to be separable from the rest of the delivery head, thedelivery assembly 150, and substantially covers the final openings orflow passages for the first, second, and third gaseous material in thedelivery device prior to the gas diffuser element. Thus, the gasdiffuser unit 140 provides essentially the final flow path for thefirst, second and third gaseous material prior to delivery from theoutput face of the delivery device to the substrate. However, the gasdiffuser element can also be designed as an inseparable part of deliveryhead.

In particular, the gas diffuser unit 140 in the embodiment of FIG. 7comprises interconnected vertically overlying passages in threevertically arranged gas diffuser components (or plates), in combinationproviding a flow path for gaseous materials. The gas diffuser unit 140provides two substantially vertical flow paths separated by asubstantially horizontal flow path, wherein each substantially verticalflow path is provided by one or more passages extending in an elongateddirection in at two elements, and wherein each substantially horizontalflow path is in a thin space between parallel surface areas of twoparallel gas diffuser components. In this embodiment, the threesubstantially horizontally extending diffuser components aresubstantially flat stacked plates, and a relatively thin space isdefined by the thickness of a central gas diffuser component (the gasdiffuser plate 146) situated between adjacent parallel gas diffusercomponents, the nozzle plate 142 and the face plate 148. However, two ofthe plates in FIG. 7 can be replaced by a single plate, in which gasdiffuser plate 146 and face plate 148 are, for example, machined orotherwise formed into a single plate. In that case, a single element orplate of the gas diffuser can have a plurality of passages each ofwhich, in perpendicular cross-section of the plate thickness takenparallel to an associated elongated emissive channel, forms an elongatedpassage parallel to the surface of the plate open at one surface of theplate, which elongated passage is integrally connected near one endthereof to a narrow vertical passage leading to the other surface of theplate. In other words, a single element could combine second and thirddiffuser passages 147 and 149 of FIG. 8D into a single element or plate.

Thus, a gas diffuser unit in accordance with the present invention canbe a multilevel system comprising a series of at least two substantiallyhorizontally extending diffuser components with parallel surfaces facingeach other in an orthogonal direction with respect to the face of thedelivery device (for example, stacked plates). In general, inassociation with each elongated emissive channel of the first, second,and third emissive channels, the gas diffuser comprises verticallyoverlying or superposed passages, respectively, in the at least twovertically arranged gas-diffuser plates, in combination providing a flowpath for gaseous material that comprises two substantially vertical flowpaths separated by a substantially horizontal flow path, wherein eachsubstantially vertical flow path is provided by one or more passages, orpassage components, extending in an elongated direction and wherein eachsubstantially horizontal flow path is provided by a thin space betweenparallel surface areas in parallel plates, wherein vertical refers tothe orthogonal direction with respect to the output face of the deliverydevice. The term component passages refers to a component of a passagein an element that does not pass all the way through the element, forexample, the two component passages formed by combining second and thirddiffuser passages 147 and 149 of FIG. 8D into a single element or plate

In the particular embodiment of FIG. 7, the gas diffuser comprises threevertically overlying sets of passages, respectively, in three verticallyarranged gas-diffuser plates, wherein a relatively thin space is definedby the thickness of a central gas diffuser plate situated between twoparallel gas diffuser plates. Two of the three diffuser components, asequentially first and third diffuser component, each comprises passagesextending in an elongated direction for the passage of gaseous material,wherein passages in the first diffuser component is horizontally offset(in a direction perpendicular to the length of the elongated direction)with respect to corresponding (interconnected) passages in the thirddiffuser component. This offset (between the passages 143 and passages149) can be better seen in FIG. 8D.

Furthermore, a sequentially second gas diffuser component positionedbetween the first and third diffuser component comprises passages 147each in the form of an elongated center opening that is relativelybroader than the width of the passages in each of the first and thirdsecond diffuser component, such that center opening is defined by twoelongated sides and contains the interconnected passages of the firstdiffuser component and the third diffuser component, respectively,within its borders when viewed from above the gas diffuser looking down.Consequently, the gas diffuser unit 140 is capable of substantiallydeflecting the flow of the gaseous material passing therethrough.Preferably, the deflection is at an angle of 45 to 135 degrees,preferably about 90 degrees, such that orthogonal gas flow is changed toparallel gas flow with respect to the surface of the output face and/orsubstrate. Thus, the flow of the gaseous material can be substantiallyvertical through the passages in the first and third gas diffusercomponents and substantially horizontal in the second gas diffusercomponent.

In the embodiment of FIG. 7, each of a plurality of passages in thefirst gas diffuser component comprises a series of holes or perforationsextending along an elongated line, wherein the correspondinginterconnected passages in the third diffuser component is an elongatedrectangular slot, which is optionally not squared at the ends. (Thus,more than one passage in the first gas diffuser component can connectwith a single passage in a subsequent gas diffuser component.)

Alternatively, as indicated above, a gas diffuser can comprise a porousmaterial, wherein the delivery device is designed such that each of theindividual emissive elongated channels provide gaseous materialindirectly to the substrate after passing through the porous materialeither within each individual emissive elongated channel and/or upstreamof each of the emissive elongated channel. Porous materials typicallycomprise pores that are formed by a chemical transformation or presentin a naturally occurring porous material.

Referring back to FIG. 4, the combination of components shown asconnection plate 100, gas chamber plate 110, gas direction plate 120,and base plate 130 can be grouped to provide a delivery assembly 150.Alternate embodiments are possible for delivery assembly 150, includingone formed from vertical, rather than horizontal, apertured plates,using the coordinate arrangement and view of FIG. 4.

Apertured plates used for delivery head 10 could be formed and coupledtogether in a number of ways. Advantageously, apertured plates can beseparately fabricated, using known methods such as progressive die,molding, machining, or stamping. Combinations of apertured plates canvary widely from those shown in the embodiments of FIGS. 4 and 9A-9B,forming delivery head 10 with any number of plates, such as from 5 to100 plates. Stainless steel is used in one embodiment and isadvantageous for its resistance to chemicals and corrosion. Generally,apertured plates are metallic, although ceramic, glass, or other durablematerials may also be suitable for forming some or all of the aperturedplates, depending on the application and on the reactant gaseousmaterials that are used in the deposition process.

For assembly, apertured plates can be glued or coupled together usingmechanical fasteners, such as bolts, clamps, or screws. For sealing,apertured plates can be skin-coated with suitable adhesive or sealantmaterials, such as vacuum grease. Epoxy, such as a high-temperatureepoxy, can be used as an adhesive. Adhesive properties of melted polymermaterials such as polytetrafluoroethylene (PTFE) or TEFLON have alsobeen used to bond together superposed apertured plates for delivery head10. In one embodiment, a coating of PTFE is formed on each of theapertured plates used in delivery head 10. The plates are stacked(superposed) and compressed together while heat is applied near themelting point of the PTFE material (nominally 327 degrees C.). Thecombination of heat and pressure then forms delivery head 10 from thecoated apertured plates. The coating material acts both as an adhesiveand as a sealant. Kapton and other polymer materials could alternatelybe used as interstitial coating materials for adhesion.

As shown in FIGS. 4 and 9B, apertured plates must be assembled togetherin the proper sequence for forming the network of interconnecting supplychambers and directing channels that route gaseous materials to outputface 36. When assembled together, a fixture providing an arrangement ofalignment pins or similar features could be used, where the arrangementof orifices and slots in the apertured plates mate with these alignmentfeatures.

Referring to FIG. 9A, there is shown, from a bottom view (that is,viewed from the gas emission side) an alternate arrangement that can beused for delivery assembly 150 using a stack of vertically disposedplates or superposed apertured plates that are disposed perpendicularlywith respect to output face 36. For simplicity of explanation, theportion of delivery assembly 150 shown in the “vertical” embodiment ofFIG. 9A has two elongated emissive channels 152 and two elongatedexhaust channels 154. The vertical plates arrangement of FIGS. 9-Athrough 13C can be readily expanded to provide a number of emissive andexhaust elongated channels. With apertured plates disposedperpendicularly with respect to the plane of output face 36, as in FIGS.9A and 9B, each elongated emissive channel 152 is formed by having sidewalls defined by separator plates, shown subsequently in more detail,with a reactant plate centered between them. Proper alignment ofapertures then provides fluid communication with the supply of gaseousmaterial.

The exploded view of FIG. 9B shows the arrangement of apertured platesused to form the small section of delivery assembly 150 that is shown inFIG. 9A. FIG. 9C is a plan view showing a delivery assembly 150 havingfive channels for emitted gases and formed using stacked aperturedplates. FIGS. 10A through 13B then show the various plates in both planand perspective views. For simplicity, letter designations are given toeach type of apertured plate: Separator S, Purge P, Reactant R, andExhaust E.

From left to right in FIG. 9B are separator plates 160 (S), also shownin FIGS. 10A and 10B, alternating between plates used for directing gastoward or away from the substrate. A purge plate 162 (P) is shown inFIGS. 11A and 11B. An exhaust plate 164 (E) is shown in FIGS. 12A and12B. A reactant plate 166 (R) is shown in FIGS. 13A and 13B. FIG. 13Cshows a reactant plate 166′ obtained by flipping the reactant plate 166of FIG. 12A horizontally; this alternate orientation can also be usedwith exhaust plate 164, as required. Apertures 168 in each of the platesalign when the plates are superposed, thus forming ducts to enable gasto be passed through delivery assembly 150 into elongated emissiveoutput channels 152 and elongated exhaust channels 154, as weredescribed with reference to FIG. 1. (The term “superposed” or“superposition” has its conventional meaning, wherein elements are laidatop or against one another in such manner that parts of one elementalign with corresponding parts of another and that their perimetersgenerally coincide.)

Returning to FIG. 9B, only a portion of a delivery assembly 150 isshown. The plate structure of this portion can be represented using theletter abbreviations assigned earlier, that is:

S-P-S-E-S-R-S-E-S

(With the last separator plate in this sequence not shown in FIG. 9A or9B.) As this sequence shows, separator plates 160 (S) define eachchannel by forming side walls. A minimal delivery assembly 150 forproviding two reactive gases along with the necessary purge gases andexhaust channels for typical ALD deposition would be represented usingthe full abbreviation sequence:

S-P-S-E1-S-R1-S-E1-S-P-S-E2-S-R2-S-E2-S-P-S-E1-S-R1-S-E1-S-P-S-E2-S-R2-S-E2-S-P-S-E1-S-R1-S-E1-S-P-S

where R1 and R2 represent reactant plates 166 in different orientations,for the two different reactant gases used, and E1 and E2 correspondinglyrepresent exhaust plates 164 in different orientations.

Elongated exhaust channel 154 need not be a vacuum port, in theconventional sense, but may simply be provided to draw off the flow inits corresponding output channel 12, thus facilitating a uniform flowpattern within the channel. A negative draw, just slightly less than theopposite of the gas pressure at neighboring elongated emissive channels152, can help to facilitate an orderly flow. The negative draw can, forexample, operate with draw pressure at the source (for example, a vacuumpump) of between 0.2 and 1.0 atmosphere, whereas a typical vacuum is,for example, below 0.1 atmosphere.

Use of the flow pattern provided by delivery head 10 provides a numberof advantages over conventional approaches, such as those noted earlierin the background section, that pulse gases individually to a depositionchamber. Mobility of the deposition apparatus improves, and the deviceof the present invention is suited to high-volume depositionapplications in which the substrate dimensions exceed the size of thedeposition head. Flow dynamics are also improved over earlierapproaches.

The flow arrangement used in the present invention allows a very smalldistance D between delivery head 10 and substrate 20, as was shown inFIG. 1, preferably under 1 mm. Output face 36 can be positioned veryclosely, to within about 1 mil (approximately 0.025 mm) of the substratesurface. The close positioning is facilitated by the gas pressuregenerated by the reactant gas flows. By comparison, CVD apparatusrequires significantly larger separation distances. Earlier approachessuch as that described in the U.S. Pat. No. 6,821,563 to Yudovsky, citedearlier, were limited to 0.5 mm or greater distance to the substratesurface, whereas embodiments of the present invention can be practice atless than 0.5 mm, for example, less than 0.450 mm. In fact, positioningthe delivery head 10 closer to the substrate surface is preferred in thepresent invention. In a particularly preferred embodiment, distance Dfrom the surface of the substrate can be 0.20 mm or less, preferablyless than 100 μm.

It is desirable that when a large number of plates are assembled in astacked-plate embodiment, the gas flow delivered to the substrate isuniform across all of the channels delivering a gas flow (I, M, or Omaterials). This can be accomplished by proper design of the aperturedplates, such as having restrictions in some part of the flow pattern foreach plate which are accurately machined to provide a reproduciblepressure drop for each emissive elongated output or exhaust channel. Inone embodiment, output channels 12 exhibit substantially equivalentpressure along the length of the openings, to within no more than about10% deviation. Even higher tolerances could be provided, such asallowing no more than about 5% or even as little as 2% deviation.

Although the method using stacked apertured plates is a particularlyuseful way of constructing a delivery head, there are a number of othermethods for building such structures that may be useful in alternateembodiments. For example, the apparatus may be constructed by directmachining of a metal block, or of several metal blocks adhered together.Furthermore, molding techniques involving internal mold features can beemployed, as will be understood by the skilled artisan. The apparatuscam also be constructed using any of a number of stereolithographytechniques.

In one embodiment of the invention, the delivery head 10 of the presentinvention can be maintained a suitable separation distance D (FIG. 1)between its output face 36 and the surface of substrate 20, by using afloating system. FIG. 14 shows some considerations for maintainingdistance D using the pressure of gas flows emitted from delivery head10.

In FIG. 14, a representative number of output channels 12 and exhaustchannels 22 are shown. The pressure of emitted gas from one or more ofoutput channels 12 generates a force, as indicated by the downward arrowin this figure. In order for this force to provide a useful cushioningor “air” bearing (fluid gas bearing) effect for delivery head 10, theremust be sufficient landing area, that is, solid surface area alongoutput face 36 that can be brought into close contact with thesubstrate. The percentage of landing area corresponds to the relativeamount of solid area of output face 36 that allows build-up of gaspressure beneath it. In simplest terms, the landing area can be computedas the total area of output face 36 minus the total surface area ofoutput channels 12 and exhaust channels 22. This means that totalsurface area, excluding the gas flow areas of output channels 12, havinga width w1, or of exhaust channels 22, having a width w2, must bemaximized as much as possible. A landing area of 95% is provided in oneembodiment. Other embodiments may use smaller landing area values, suchas 85% or 75%, for example. Adjustment of gas flow rate could also beused in order to alter the separation or cushioning force and thuschange distance D accordingly.

It can be appreciated that there would be advantages to providing anfluid gas bearing, so that delivery head 10 is substantially maintainedat a distance D above substrate 20. This would allow essentiallyfrictionless motion of delivery head 10 using any suitable type oftransport mechanism. Delivery head 10 could then be caused to “hover”above the surface of substrate 20 as it is channeled back and forth,sweeping across the surface of substrate 20 during materials deposition.

As shown in FIG. 14, delivery head 10 may be too heavy, so that thedownward gas force is not sufficient for maintaining the neededseparation. In such a case, auxiliary lifting components, such as aspring 170, magnet, or other device, could be used to supplement thelifting force. In other cases, gas flow may be high enough to cause theopposite problem, so that delivery head 10 would be forced apart fromthe surface of substrate 20 by too great a distance, unless additionalforce is exerted. In such a case, spring 170 may be a compressionspring, to provide the additional needed force to maintain distance D(downward with respect to the arrangement of FIG. 14). Alternately,spring 170 may be a magnet, elastomeric spring, or some other devicethat supplements the downward force.

Alternately, delivery head 10 may be positioned in some otherorientation with respect to substrate 20. For example, substrate 20could be supported by the fluid gas bearing effect, opposing gravity, sothat substrate 20 can be moved along delivery head 10 during deposition.One embodiment using the fluid gas bearing effect for deposition ontosubstrate 20, with substrate 20 cushioned above delivery head 10 isshown in FIG. 20. Movement of substrate 20 across output face 36 ofdelivery head 10 is in a direction along the double arrow as shown.

The alternate embodiment of FIG. 21 shows substrate 20 on a substratesupport 74, such as a web support or rollers, moving in direction Kbetween delivery head 10 and a fluid gas bearing 98. In this case, airor another inert gas alone can be used. In this embodiment, deliveryhead 10 has an air-bearing effect and cooperates with gas fluid bearing98 in order to maintain the desired distance D between output face 36and substrate 20. Gas fluid bearing 98 may direct pressure using a flowF4 of inert gas, or air, or some other gaseous material. It is notedthat, in the present deposition system, a substrate support or holdercan be in contact with the substrate during deposition, which substratesupport can be a means for conveying the substrate, for example aroller. Thus, thermal isolation of the substrate being treated is not arequirement of the present system.

As was particularly described with reference to FIGS. 3A and 3B,delivery head 10 requires movement relative to the surface of substrate20 in order to perform its deposition function. This relative movementcan be obtained in a number of ways, including movement of either orboth delivery head 10 and substrate 20, such as by movement of anapparatus that provides a substrate support. Movement can be oscillatingor reciprocating or could be continuous movement, depending on how manydeposition cycles are needed. Rotation of a substrate can also be used,particularly in a batch process, although continuous processes arepreferred. An actuator may be coupled to the body of the delivery head,such as mechanically connected. An alternating force, such as a changingmagnetic force field, could alternately be used.

Typically, ALD requires multiple deposition cycles, building up acontrolled film depth with each cycle. Using the nomenclature for typesof gaseous materials given earlier, a single cycle can, for example in asimple design, provide one application of first reactant gaseousmaterial O and one application of second reactant gaseous material M.

The distance between output channels for O and M reactant gaseousmaterials determines the needed distance for reciprocating movement tocomplete each cycle. For the example delivery head 10 of FIG. 4 may havea nominal channel width of 0.1 inches (2.54 mm) in width between areactant gas channel outlet and the adjacent purge channel outlet.Therefore, for the reciprocating motion (along the y axis as usedherein) to allow all areas of the same surface to see a full ALD cycle,a stroke of at least 0.4 inches (10.2 mm) would be required. For thisexample, an area of substrate 20 would be exposed to both first reactantgaseous material O and second reactant gaseous material M with movementover this distance. Alternatively, a delivery head can move much largerdistances for its stroke, even moving from one end of a substrate toanother. In this case the growing film may be exposed to ambientconditions during periods of its growth, causing no ill effects in manycircumstances of use. In some cases, consideration for uniformity mayrequire a measure of randomness to the amount of reciprocating motion ineach cycle, such as to reduce edge effects or build-up along theextremes of reciprocation travel.

A delivery head 10 may have only enough output channels 12 to provide asingle cycle. Alternately, delivery head 10 may have an arrangement ofmultiple cycles, enabling it to cover a larger deposition area orenabling its reciprocating motion over a distance that allows two ormore deposition cycles in one traversal of the reciprocating motiondistance.

For example, in one particular application, it was found that each O-Mcycle formed a layer of one atomic diameter over about ¼ of the treatedsurface. Thus, four cycles, in this case, are needed to form a uniformlayer of 1 atomic diameter over the treated surface. Similarly, to forma uniform layer of 10 atomic diameters in this case, then, 40 cycleswould be required.

An advantage of the reciprocating motion used for a delivery head 10 ofthe present invention is that it allows deposition onto a substrate 20whose area exceeds the area of output face 36. FIG. 15 showsschematically how this broader area coverage can be effected, usingreciprocating motion along the y axis as shown by arrow A and alsomovement orthogonal or transverse to the reciprocating motion, relativeto the x axis. Again, it must be emphasized that motion in either the xor y direction, as shown in FIG. 15, can be effected either by movementof delivery head 10, or by movement of substrate 20 provided with asubstrate support 74 that provides movement, or by movement of bothdelivery head 10 and substrate 20.

In FIG. 15 the relative motion directions of the delivery head, whichcan comprise a distribution manifold, and the substrate areperpendicular to each other. It is also possible to have this relativemotion in parallel. In this case, the relative motion needs to have anonzero frequency component that represents the oscillation and a zerofrequency component that represents the displacement of the substrate.This combination can be achieved by: an oscillation combined withdisplacement of the delivery head over a fixed substrate; an oscillationcombined with displacement of the substrate relative to a fixedsubstrate delivery head; or any combinations wherein the oscillation andfixed motion are provided by movements of both the delivery head and thesubstrate.

Advantageously, delivery head 10 can be fabricated at a smaller sizethan is possible for many types of deposition heads. For example, in oneembodiment, output channel 12 has width w1 of about 0.005 inches (0.127mm) and is extended in length to about 3 inches (75 mm).

In a preferred embodiment, ALD can be performed at or near atmosphericpressure and over a broad range of ambient and substrate temperatures,preferably at a temperature of under 300° C. Preferably, a relativelyclean environment is needed to minimize the likelihood of contamination;however, full “clean room” conditions or an inert gas-filled enclosurewould not be required for obtaining good performance when usingpreferred embodiments of the apparatus of the present invention.

FIG. 16 shows an Atomic Layer Deposition (ALD) system 60 having achamber 50 for providing a relatively well-controlled andcontaminant-free environment. Gas supplies 28 a, 28 b, and 28 c providethe first, second, and third gaseous materials to delivery head 10through supply lines 32. The optional use of flexible supply lines 32facilitates ease of movement of delivery head 10. For simplicity,optional vacuum vapor recovery apparatus and other support componentsare not shown in FIG. 16 but could also be used. A transport subsystem54 provides a substrate support that conveys substrate 20 along outputface 36 of delivery head 10, providing movement in the x direction,using the coordinate axis system employed in the present disclosure.Motion control, as well as overall control of valves and othersupporting components, can be provided by a control logic processor 56,such as a computer or dedicated microprocessor assembly, for example. Inthe arrangement of FIG. 16, control logic processor 56 controls anactuator 30 for providing reciprocating motion to delivery head 10 andalso controls a transport motor 52 of transport subsystem 54. Actuator30 can be any of a number of devices suitable for causing back-and-forthmotion of delivery head 10 along a moving substrate 20 (or, alternately,along a stationary substrate 20).

FIG. 17 shows an alternate embodiment of an Atomic Layer Deposition(ALD) system 70 for thin film deposition onto a web substrate 66 that isconveyed past delivery head 10 along a web conveyor 62 that acts as asubstrate support. The web itself may be the substrate being treated ormay provide support for a substrate, either another web or separatesubstrates, for example, wafers. A delivery head transport 64 conveysdelivery head 10 across the surface of web substrate 66 in a directiontransverse to the web travel direction. In one embodiment, delivery head10 is impelled back and forth across the surface of web substrate 66,with the full separation force provided by gas pressure. In anotherembodiment, delivery head transport 64 uses a lead screw or similarmechanism that traverses the width of web substrate 66. In anotherembodiment, multiple delivery heads 10 are used, at suitable positionsalong web conveyor 62.

FIG. 18 shows another Atomic Layer Deposition (ALD) system 70 in a webarrangement, using a stationary delivery head 10 in which the flowpatterns are oriented orthogonally to the configuration of FIG. 17. Inthis arrangement, motion of web conveyor 62 itself provides the movementneeded for ALD deposition. Reciprocating motion could also be used inthis environment. Referring to FIG. 19, an embodiment of a portion ofdelivery head 10 is shown in which output face 36 has an amount ofcurvature, which might be advantageous for some web coatingapplications. Convex or concave curvature could be provided.

In another embodiment that can be particularly useful for webfabrication, ALD system 70 can have multiple delivery heads 10, or dualdelivery heads 10, with one disposed on each side of web substrate 66. Aflexible delivery head 10 could alternately be provided. This wouldprovide a deposition apparatus that exhibits at least some conformanceto the deposition surface.

In still another embodiment, one or more output channels 12 of deliveryhead 10 may use the transverse gas flow arrangement that was disclosedin U.S. application Ser. No. 11/392,006, filed Mar. 29, 2006 by Levy etal. and entitled “APPARATUS FOR ATOMIC LAYER DEPOSITION,” cited earlierand incorporated herein by reference. In such an embodiment, gaspressure that supports separation between delivery head 10 and substrate20 can be maintained by some number of output channels 12, such as bythose channels that emit purge gas (channels labeled I in FIGS. 2-3B),for example. Transverse flow would then be used for one or more outputchannels 12 that emit the reactant gases (channels labeled O or M inFIGS. 2-3B).

The apparatus of the present invention is advantaged in its capabilityto perform deposition onto a substrate over a broad range oftemperatures, including room or near-room temperature in someembodiments. The apparatus of the present invention can operate in avacuum environment, but is particularly well suited for operation at ornear atmospheric pressure.

Thin film transistors having a semiconductor film made according to thepresent method can exhibit a field effect electron mobility that isgreater than 0.01 cm²/Vs, preferably at least 0.1 cm²/Vs, morepreferably greater than 0.2 cm²/Vs. In addition, n-channel thin filmtransistors having semiconductor films made according to the presentinvention are capable of providing on/off ratios of at least 10⁴,advantageously at least 10⁵. The on/off ratio is measured as themaximum/minimum of the drain current as the gate voltage is swept fromone value to another that are representative of relevant voltages whichmight be used on the gate line of a display. A typical set of valueswould be −10V to 40V with the drain voltage maintained at 30V.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention as described above, and as noted in the appended claims, by aperson of ordinary skill in the art without departing from the scope ofthe invention. For example, while air bearing effects may be used to atleast partially separate delivery head 10 from the surface of substrate20, the apparatus of the present invention may alternately be used tolift or levitate substrate 20 from output surface 36 of delivery head10. Other types of substrate holder could alternately be used, includinga platen for example.

EXAMPLE 1

A mechanical gas diffusing element according to the embodiment of FIG.8D was constructed. In this element, the 130 micron thick nozzle platecontained 50 micron holes at a spacing of 1000 microns. The mixingchamber was composed of an additional 130 thick micron plate in whichexisted chamber openings of 460 microns. Finally, the gas was allowed toexit through and additional 130 thick micron plate in which were cut 100micron exit slots.

The diffuser plate was mounted to a fixture to allow a flow to bepresented to the nozzle arrangement. The cumulative area of flow forthis setup, as defined by the area between exit slots, was 9.03×10⁻⁴ m².A total volumetric flow of 5.46×10⁻⁵ m³/s of nitrogen (density=1.14kg/m³) was flowed through the device, leading to a gas velocity of 0.06m/s. With this gas velocity, a pressure drop of 2760 Pa was measuredacross the diffuser. Pressure was measured with a commercially availabledigital pressure transducer/gauge (obtained from Omega). Since thedefinition of a friction factor relates it to the force exerted by theflow on the gas diffuser, the measured pressure drop is in terms offorce/area, not the force directly. The friction factor f was calculatedto be 1.3×10⁶.

Using an APALD device according to the embodiment of FIG. 4 comprisingthis mechanical gas diffusing element, a film of Al₂O₃ was grown on asilicon wafer, according to the present invention. The APALD device wasconfigured to have 11 output channels in a configuration as follows:

Channel 1: Purge Gas Channel 2: Oxidizer containing gas Channel 3: PurgeGas Channel 4: Metal precursor containing gas Channel 5: Purge GasChannel 6: Oxidizer containing gas Channel 7: Purge Gas Channel 8: Metalprecursor containing gas Channel 9: Purge Gas Channel 10: Oxidizercontaining gas Channel 11: Purge Gas

The film was grown at a substrate temperature of 150° C. Gas flowsdelivered to the APALD coating head were as follows:

(i) A nitrogen inert purge gas was supplied to channels 1, 3, 5, 7, 9,and 11 at a total flow rate of 3000 sccm.

(ii) A nitrogen based gas stream containing trimethylaluminum wassupplied to channels 4 and 8. This gas stream was produced by mixing aflow of ˜400 sccm of pure nitrogen with a flow of 3.5 sccm of nitrogensaturated with TMA at room temperature.

(iii) A nitrogen based gas stream containing water vapor was supplied tochannels 2, 6, and 10. This gas stream was produced by mixing a flow of˜350 sccm of pure nitrogen with a flow of 20 sccm of nitrogen saturatedwith water vapor at room temperature.

The coating head with the above gas supply streams was brought intoproximity with the substrate and then released, so that it floated abovethe substrate based upon the gas flows as described earlier. At thispoint, the coating head was oscillated for 300 cycles across thesubstrate to yield an Al₂O₃ film of approximately 900 Å thickness.

A current leakage test structure was formed by coating aluminum contactpads on top of the Al₂O₃ layer using a shadow mask during an aluminumevaporation. This process resulted in aluminum contact pads on top ofthe Al₂O₃ that were approximately 500 Å thick with an area of 500microns×200 microns.

The leakage current from the silicon wafer to the Al contacts wasmeasured by applying a 20V potential between a given aluminum contactpad to the silicon wafer and measuring the amount the current flow withan HP-4155C® parameter analyzer. At a 20 V potential, the leakagethrough the Al₂O₃ dielectric was 1.3×10⁻¹¹ A. As can be seen from thistest data, the coating head of this example produces a film withadvantageously low current leakage, which is desired for the productionof useful dielectric films.

EXAMPLE 2

Instead of the mechanical gas diffusing element of Example 1, a 0.2micron pore porous alumina membrane can be used. A commerciallyavailable alumina porous membrane containing 0.2 micron pores waspurchased from Whatman Incorporated. The active area of the membrane was19 mm in diameter and was mounted in a pressure filter holder throughwhich was passed nitrogen gas at room temperature. The cumulative areaof flow for this setup, as defined by the area of the 19 mm diametercircle, was 2.83×10⁻⁴ m². A total volumetric flow of 1.82×10⁵ m³/s ofnitrogen (density=1.14 kg/m³) was flowed through the device, leading toa gas velocity of 0.06 m/s. With this gas velocity, a pressure drop of22690 Pa was measured across the diffuser. The friction factor f wascalculated to be 9.6×10⁶.

EXAMPLE 3

Instead of the mechanical gas diffusing element of Example 1, a 0.02micron pore porous alumina membrane can be used. A commerciallyavailable alumina porous membrane containing 0.02 micron pores waspurchased from Whatman Incorporated. The active area of the membrane was19 mm in diameter and was mounted in a pressure filter holder throughwhich was passed gas at room temperature. The cumulative area of flowfor this setup, as defined by the area of the 19 mm diameter circle, was2.83×10⁻⁴ m². A total volumetric flow of 1.82×10⁵ m³/s of nitrogen(density=1.14 kg/m³) was flowed through the device, leading to a gasvelocity of 0.06 m/s. With this gas velocity, a pressure drop of 54830Pa was measured across the plate. The friction factor f was calculatedto be 2.3×10⁷.

COMPARATE EXAMPLE 4

Instead of the mechanical gas diffusing element of Example 1, thefriction factor or a metal screen with 150 micron perforations wasdetermined. A commercially available metal screen was obtained from theMcMaster Carr company. The screen was 250 microns thick, with 150 microncircular perforations. The perforations were spaced at 300 microns oncenter in a hexagonal pattern. This screen represents a fairly smallhole size for commercially available metal screens.

A piece of screen was mounted in a holder with gas allowed to passthrough a square cross section of the screen measuring 1.5 mm×2.3 mm. Atotal volumetric flow of 1.82×10⁻⁵ m³/s of nitrogen (density=1.14 kg/m³)was flowed through the device, leading to a gas velocity of 5.27 m/s.With this gas velocity, a pressure drop of 480 Pa was measured acrossthe screen. The friction factor f was calculated to be 3.0×10¹.

A larger velocity of gas flow was used for this measurement due to thefact that this screen had a very low friction factor and needed a highgas velocity in order to produce a measurable pressure drop. The lowfriction factor produced by this screen, despite the fact that it is ofa design that should provide some resistance to flow, indicates thatthis screen by itself could not provide a friction factor greater than1×10².

PARTS LIST

-   10 delivery head-   12 output channel-   14, 16, 18 gas inlet conduit-   20 substrate-   22 exhaust channel-   24 exhaust conduit-   28 a, 28 b, 28 c gas supply-   30 actuator-   32 supply line-   36 output face-   50 chamber-   52 transport motor-   54 transport subsystem-   56 control logic processor-   60 Atomic Layer Deposition (ALD) system-   62 web conveyor-   64 delivery head transport-   66 web substrate-   70 Atomic Layer Deposition (ALD) system-   74 substrate support-   90 directing channel for precursor material-   91 exhaust directing channel-   92 directing channel for purge gas-   96 substrate support-   98 gas fluid bearing-   100 connection plate-   102 directing chamber-   104 input port-   110 gas chamber plate-   112, 113, 115, supply chamber-   114, 116 exhaust chamber-   120 gas direction plate-   122 directing channel for precursor material-   123 exhaust directing channel-   130 base plate-   132 elongated emissive channel-   134 elongated exhaust channel-   140 gas diffuser unit-   142 nozzle plate-   143, 147, 149 first, second, third diffuser passages-   146 gas diffuser plate-   148 face plate-   150 delivery assembly-   152 elongated emissive channel-   154 elongated exhaust channel-   160 separator plate-   162 purge plate-   164 exhaust plate-   166, 166′ reactant plate-   168 aperture-   170 spring-   180 sequential first exhaust slot-   182 sequential second exhaust slot-   184 sequential third exhaust slot-   A arrow-   D distance-   E Exhaust plate-   F1, F2, F3, F4 gas flow-   I third inert gaseous material-   K direction-   M second reactant gaseous material-   O first reactant gaseous material-   P purge plate-   R reactant plate-   S separator plate-   w1, w2 channel width-   X arrow

1. A delivery device for thin-film material deposition onto a substratecomprising: (a) a plurality of inlet ports comprising at least a firstinlet port, a second inlet port, and a third inlet port capable ofreceiving a common supply for a first gaseous material, a second gaseousmaterial, and a third gaseous material, respectively; (b) at least oneexhaust port capable of receiving exhaust gas from thin-film materialdeposition and at least two elongated exhaust channels, each of theelongated exhaust channels capable of gaseous fluid communication withthe at least one exhaust port; (c) at least three groups of elongatedemissive channels, (i) a first group comprising one or more firstelongated emissive channels, (ii) a second group comprising one or moresecond elongated emissive channels, and (iii) a third group comprisingat least two third elongated emissive channels, each of the first,second, and third elongated emissive channels capable of gaseous fluidcommunication, respectively unmixed, with one of the corresponding firstinlet port, second inlet port, and third inlet port; wherein each of thefirst, second, and third elongated emissive channels and each of theelongated exhaust channels extend in a length direction substantially inparallel; wherein each first elongated emissive channel is separated onat least one elongated side thereof from a nearest second elongatedemissive channel by a relatively nearer elongated exhaust channel and arelatively less near third elongated emissive channel; wherein eachfirst elongated emissive channel and each second elongated emissivechannel is situated between relatively nearer elongated exhaust channelsand between relatively less nearer elongated emissive channels; (d) agas diffuser associated with at least one group of the three groups ofelongated emissive channels such that at least one of the first, second,and third gaseous material, respectively, is capable of passing throughthe gas diffuser prior to delivery from the delivery device to thesubstrate, during thin-film material deposition onto the substrate, andwherein the gas diffuser maintains flow isolation of the at least one offirst, second, and third gaseous material downstream from each of theelongated emissive channels in the at least one group of elongatedemissive channels; wherein the gas diffuser is capable of providing afriction factor that is greater than 1×10², assuming a representativegas that is nitrogen at 25° C. and a representative average velocitybetween 0.01 and 0.5 m/sec of gaseous material passing through the gasdiffuser.
 2. The delivery device of claim 1 wherein the gas diffuser isassociated with each of the three groups of elongated emissive channelssuch that each of the first, second, and third gaseous material,respectively, is capable of separately passing from the delivery deviceto the substrate during thin-film material deposition on the substrate,and wherein the gas diffuser maintains flow isolation of each of first,second, and third gaseous material downstream from each of the elongatedemissive channels in the three groups of elongated emissive channels. 3.The delivery device of claim 2 wherein the gas diffuser is a mechanicalassembly housing separate flow paths associated with each of the firstelongated emissive channels, separate flow paths associated with each ofthe second elongated emissive channels, and separate flow pathsassociated with each of the third elongated emissive channels.
 4. Thedelivery device of claim 1 wherein the gas diffuser occupies at least aportion of each of the individual elongated emissive channels in the atleast one of the three groups of elongated emissive channels.
 5. Thedelivery device of claim 1 wherein the gas diffuser element is capableof providing a friction factor that is between 1×10⁴ to 1×10⁸.
 6. Thedelivery device of claim 1 wherein there are at least two secondelongated emissive channels and wherein each first elongated emissivechannel is separated on both elongated sides thereof from the nearestsecond elongated emissive channel by a relatively nearer elongatedexhaust channel and a relatively less near third elongated emissivechannel.
 7. The delivery device of claim 1 wherein there are a pluralityof second elongated emissive channels and a plurality of first elongatedemissive channels; wherein each first elongated emissive channel isseparated on both elongated sides thereof from the nearest secondelongated emissive channel by a relatively nearer elongated exhaustchannel and a relatively less near third elongated emissive channel; andwherein each second elongated emissive channel is separated on bothelongated sides thereof from the nearest first elongated emissivechannel by a relatively nearer elongated exhaust channel and arelatively less near third elongated emissive channel.
 8. The deliverydevice of claim 7 wherein the delivery device comprises an additionalfirst or second elongated emissive channel at each of two ends of thedelivery head that does not have, on one side thereof, a second or firstelongated emissive channel, respectively, on the side closest to an edgeof an output face of the delivery device.
 9. The delivery device ofclaim 2 wherein the gas diffuser is a unit that is designed to beseparable from a delivery assembly, comprising the rest of the deliverydevice, and that substantially covers the most downstream flow passagesof the delivery assembly for the first, second, and third gaseousmaterial.
 10. The delivery device of claim 1 wherein the gas diffuser isdesigned to be an inseparable part of the delivery device.
 11. Thedelivery device of claim 1 wherein the gas diffuser comprises amechanically formed assembly comprising interconnected openings in atleast two elements, thereby providing the required friction factor. 12.The delivery device of claim 11 wherein the at least two elements aresteel, and the interconnected openings are formed by molding, mechanicalmachining, or laser or lithographic techniques.
 13. The delivery deviceof claim 2 wherein for each individual first, second, and thirdelongated emissive channel, the gas diffuser comprises at least twovertically overlying passages, respectively, in at least two verticallyarranged gas-diffuser plates, in combination providing a flow path forgaseous material that comprises two substantially vertical flow pathsseparated by a substantially horizontal flow path, wherein thesubstantially vertical flow path is provided by passages, or componentsof passages, extending in an elongated direction parallel tocorresponding elongated emissive channels, and wherein the substantiallyhorizontal flow path is provided by a relatively thin space betweenparallel surface areas in parallel gas diffuser plates, wherein verticalrefers to the orthogonal direction with respect to an output face of thedelivery device.
 14. The delivery device of claim 13 wherein the atleast two vertically arranged gas diffuser plates have substantiallyhorizontally extending surfaces on each side and form substantiallyflat, stacked apertured plates.
 15. The delivery device of claim 13wherein the gas diffuser comprises at least three vertically overlyingsets of passages, respectively, in at least three vertically arrangedgas diffuser plates, wherein the relatively thin space is defined by athickness of a central gas diffuser plate situated between twosubstantially parallel gas diffuser plates.
 16. The delivery device ofclaim 1 wherein the gas diffuser is a multilevel system comprising aseries of at least three substantially horizontally extending gasdiffuser plates with substantially parallel surfaces facing each otherin an orthogonal direction with respect to an output face of thedelivery device, each of said gas diffuser plates having a plurality offlow passages each in gaseous communication with one of the individualelongated emissive channels among the first, second, and third elongatedemissive channels; wherein the plurality of passages in at least two ofthe gas diffuser plates, a sequential first and third diffuser plate,extends in an elongated direction, and wherein the each of the pluralityof passages in the first gas diffuser plate is horizontally offset, in adirection perpendicular to the length of the elongated direction, withrespect to the each of the plurality of passages in the third diffuserplates that is in gaseous fluid communication therewith; wherein asequentially second gas diffuser plate positioned between the first andthird diffuser plate comprises a plurality of elongated center openingseach of which is relatively broader than the width of the correspondingpassages in flow communication thereof in each of the first and thethird second diffuser plates, such that each elongated center opening isdefined by two elongated sides and from the vertical direction containswithin its borders the horizontally offset passages, of the firstdiffuser component and the third diffuser plate, in flow communicationtherewith; and whereby the gas diffuser is capable of substantiallydeflecting flow of gaseous material passing therethrough.
 17. Thedelivery device of claim 11 wherein the gas diffuser unit is capable ofdeflecting flow at an angle of 45 to 135 degrees, such that orthogonalflow is changed to a parallel flow with respect to a surface of anoutput face of the delivery device.
 18. The delivery device of claim 11wherein the gas diffuser sequentially provides (i) flow of gaseousmaterial substantially vertical through the one or more passages, orcomponents of passages in the at least two elements, and (ii) flow ofgaseous material substantially horizontally in a narrow space formedbetween substantially parallel surface areas of the at least twoelements, wherein the narrow space in vertical cross-section forms anelongated channel parallel to an associated elongated emissive channel,wherein vertical means perpendicular with respect to an output face ofthe delivery device and horizontal means parallel with respect to theoutput face of the delivery device.
 19. The delivery device of claim 16wherein the passages in the first gas diffuser plate comprises aplurality of individual sets of perforations extending along anelongated line, wherein each individual set of perforations is ingaseous flow communication with one of the passages in the second gasdiffuser plate.
 20. The delivery device of claim 1 wherein each of theelongated emissive channels in at least one group of the three groups ofelongated emissive channels are designed to provide at least one of thefirst, second, and third gaseous material indirectly to the substrateafter passing through a porous material that is either (i) within eachindividual emissive elongated channel among the at least one group ofelongated emissive channels and/or (ii) upstream of each individualemissive elongated channel among the at least one group of elongatedemissive channels.
 21. The delivery device of claim 20 in which theporous material comprises pores that are formed by a chemicaltransformation or present in a naturally occurring porous material. 22.The delivery device of claim 21 wherein the porous material comprisespores that are less than 10,000 nm in average diameter, which volume issubstantially available for flow of gaseous material.
 23. The deliverydevice of claim 20 wherein the porous material comprises pores formedfrom the interstitial space between particles or pores that areinterconnected voids in a solid material formed by a voiding agent. 24.The delivery device of claim 20 wherein the porous material is formedfrom microfibers.
 25. The delivery device of claim 20 wherein the porousmaterial comprises an isolating, non-connecting pores structure in whichpores are substantially vertical to the surface.
 26. The delivery deviceof claim 20 wherein the porous material is an alumina material made fromanodized aluminum.
 27. The delivery device of claim 20 wherein theporous material comprises one or more layers of different porousmaterials or a layer of porous material supported by a perforated sheet,which layers are optionally separated by spacer elements.
 28. Thedelivery device of claim 20 wherein the porous material comprises alayer that is 5 to 1000 micrometers thick.
 29. The delivery device ofclaim 20 wherein the porous material is formed from the interstitialspace between inorganic or organic particles which is held together bybonding.
 30. The delivery device of claim 20 wherein the porous materialresults from the processing of a polymer film to generate porosity. 31.The delivery device of claim 20 wherein the porous material is in theform of at least one horizontally disposed layer that covers the face ofthe delivery device.
 32. The delivery device of claim 20 wherein theporous material forms a continuous layer, optionally with passagesmechanically formed therein.
 33. The delivery device of claim 32 whereinthe mechanically formed openings are elongated channels for therelatively unimpeded flow of exhaust gaseous material back through thedelivery device.
 34. The delivery device of claim 20 wherein the layerof porous material is in the form of a substantially continuous plate ina stack of plates.
 35. The delivery device of claim 20 wherein the gasdiffuser is an assembly of elements in which porous material is held inseparate confined areas.
 36. The delivery device of claim 20 wherein theporous material is introduced or formed inside elongated channels,wherein the elongated channels are at least partially filled by theporous material.
 37. The delivery device of claim 36 wherein theelongated channels are elongated channels in a steel plate in whichparticles are introduced and then sintered to form a gas diffuserelement or portion thereof.
 38. A delivery device for thin-film materialdeposition onto a substrate comprising: (a) a plurality of inlet portscomprising at least a first inlet port, a second inlet port, and a thirdinlet port capable of receiving a common supply for a first gaseousmaterial, a second gaseous material, and a third gaseous material,respectively; (b) at least one exhaust port capable of receiving exhaustgas from thin-film material deposition and at least two elongatedexhaust channels, each of the elongated exhaust channels capable ofgaseous fluid communication with the at least one exhaust port; (c) atleast three groups of elongated emissive channels, (i) a first groupcomprising one or more first elongated emissive channels, (ii) a secondgroup comprising one or more second elongated emissive channels, and(iii) a third group comprising at least two third elongated emissivechannels, each of the first, second, and third elongated emissivechannels capable of gaseous fluid communication, respectively unmixed,with one of the corresponding first inlet port, second inlet port, andthird inlet port; wherein each of the first, second, and third elongatedemissive channels and each of the elongated exhaust channels extend in alength direction substantially in parallel; wherein each first elongatedemissive channel is separated on at least one elongated side thereoffrom a nearest second elongated emissive channel by a relatively nearerelongated exhaust channel and a relatively less near third elongatedemissive channel; wherein each first elongated emissive channel and eachsecond elongated emissive channel is situated between relatively nearerelongated exhaust channels and between relatively less nearer elongatedemissive channels; (d) a gas diffuser associated with at least one groupof the three groups of elongated emissive channels such that at leastone of the first, second, and third gaseous material, respectively, iscapable of passing through the gas diffuser prior to delivery from thedelivery device to the substrate, during thin-film material depositiononto the substrate, and wherein the gas diffuser maintains flowisolation of the at least one of first, second, and third gaseousmaterial downstream from each of the elongated emissive channels in theat least one group of elongated emissive channels; wherein the gasdiffuser comprises a porous material through which the at least one ofthe first, the second, and the third gaseous material passes.
 39. Adelivery device for thin-film material deposition onto a substratecomprising: (a) a plurality of inlet ports comprising at least a firstinlet port, a second inlet port, and a third inlet port capable ofreceiving a common supply for a first gaseous material, a second gaseousmaterial, and a third gaseous material, respectively; (b) at least oneexhaust port capable of receiving exhaust gas from thin-film materialdeposition and at least two elongated exhaust channels, each of theelongated exhaust channels capable of gaseous fluid communication withthe at least one exhaust port; (c) at least three groups of elongatedemissive channels, (i) a first group comprising one or more firstelongated emissive channels, (ii) a second group comprising one or moresecond elongated emissive channels, and (iii) a third group comprisingat least two third elongated emissive channels, each of the first,second, and third elongated emissive channels capable of gaseous fluidcommunication, respectively unmixed, with one of the corresponding firstinlet port, second inlet port, and third inlet port; wherein each of thefirst, second, and third elongated emissive channels and each of theelongated exhaust channels extend in a length direction substantially inparallel; wherein each first elongated emissive channel is separated onat least one elongated side thereof from a nearest second elongatedemissive channel by a relatively nearer elongated exhaust channel and arelatively less near third elongated emissive channel; wherein eachfirst elongated emissive channel and each second elongated emissivechannel is situated between relatively nearer elongated exhaust channelsand between relatively less nearer elongated emissive channels; (d) agas diffuser associated with at least one group of the three groups ofelongated emissive channels such that at least one of the first, second,and third gaseous material, respectively, is capable of passing throughthe gas diffuser prior to delivery from the delivery device to thesubstrate, during thin-film material deposition onto the substrate, andwherein the gas diffuser maintains flow isolation of the at least one offirst, second, and third gaseous material downstream from each of theelongated emissive channels in the at least one group of elongatedemissive channels; wherein the gas diffuser comprises a mechanicallyformed assembly comprising a series of at least two elements, eachelement comprising a substantially parallel surface area facing eachother; wherein at least one element comprises a plurality ofperforations extending in an elongated direction, wherein each pluralityof perforations is associated with the flow from one of the eachelongated emissive channels in the at least one group of elongatedemissive channels; and wherein the gas diffuser deflects gaseousmaterial passing from each of the plurality of perforations into a thinspace between the parallel surface areas in the two elements.
 40. Adeposition system wherein the delivery device of claim 1 is capable ofproviding thin film deposition of a solid material onto a substrate in asystem in which a substantially uniform distance is maintained betweenan output face of the delivery head and the substrate surface duringthin film deposition.
 41. The deposition system of claim 40 whereinpressures generated due to flow of one or more of the gaseous materialsfrom the delivery head to the substrate surface for thin film depositionprovides at least part of the force separating the output face of thedelivery head from the surface of the substrate.
 42. The depositionsystem of claim 40 wherein a substrate support is a moving web and/orthe substrate is a moving web.
 43. The deposition system of claim 40wherein the substrate support maintains the substrate surface at aseparation distance of within 0.4 mm of the output face of the deliveryhead.
 44. The deposition system of claim 42 wherein movement of the webprovided by the transport apparatus is continuous, optionallyreciprocating.
 45. The deposition system of claim 40 wherein thesubstrate and the delivery head are open to the atmosphere.
 46. Thedeposition system of claim 40 wherein gas flows are provided throughsubstantially parallel elongated openings on the output face of thedelivery head, which are substantially straight or substantiallyconcentric.
 47. The deposition system of claim 40 wherein thesubstantially uniform distance maintained between the output face of thedelivery head and the substrate is less than 1 mm.